Battery

Abstract

To provide a battery having a more suitable structure as a safety valve.SOLUTION: A battery includes an exterior body that contains a battery assembly and an electrolyte, and a safety valve attached to the exterior body, the battery assembly includes a positive electrode, a negative electrode, and a separator, the exterior body includes a cylindrical portion, a support portion that protrudes inward from the cylindrical portion at one end of the cylindrical portion, and an opening surrounded by the support portion, the safety valve is positioned at the one end of the cylindrical portion, and the safety valve and the support portion are fixed via a thermoplastic resin layer.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a battery, and more particularly to a battery comprising a battery assembly including a positive electrode, a negative electrode and a separator. [Background technology]

[0002] Batteries are capable of extracting 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) 2020 / 111275 [Patent Document 2] JP 2018-166023 A [Patent Document 3] International Patent Publication (WO) 2022 / 149392 [Patent Document 4] Special Publication No. 2020-509546 Summary of the Invention [Problem to be solved by the invention]

[0004] Batteries may be provided with a mechanism for ensuring their safety. For example, when an abnormality occurs in the battery and gas is generated inside the battery, a battery may be provided with a safety mechanism using a safety valve for suppressing the occurrence of malfunctions caused by the gas (Patent Documents 1 to 4). The inventors of the present application have earnestly examined whether there is still room for development of battery safety mechanisms. As a result, they have found that there is still room for development of a safety valve that can cut off current in the event of an abnormality.

[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 a more suitable structure for 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 battery includes an exterior housing that houses a battery assembly and an electrolyte, and a safety valve that is attached to the exterior housing; The battery assembly includes a positive electrode, a negative electrode, and a separator; The exterior body includes a cylindrical portion, a support portion that protrudes inward from the cylindrical portion at one end of the cylindrical portion, and an opening portion that is surrounded by the support portion, the safety valve is located at the one end of the barrel; The safety valve and the support portion are fixed together via a thermoplastic resin layer. Effect of the Invention

[0008] In the battery according to the present invention, a safety valve is disposed outside the exterior body. The exterior body and the safety valve are fixed by a thermoplastic resin layer interposed between the exterior body and the safety valve. With this structure, when the temperature of the battery rises and gas is abnormally generated inside the battery, the fixed portion made of the thermoplastic resin is cleaved, allowing the gas inside the battery to be released to the outside. This makes it possible to suppress or avoid the explosion of a battery whose internal pressure has abnormally increased due to gas generation, and to deal with the problem safely. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view showing the appearance of a battery according to one embodiment of the present invention. [Diagram 2]FIG. 2 is a schematic diagram showing the internal configuration of a 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 battery according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view of components of a safety valve of a battery according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view showing a state before the safety valve of the battery according to one embodiment of the present invention is activated. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a state after the safety valve of the battery according to one embodiment of the present invention has been activated. [Figure 7] FIG. 7 is a schematic cross-sectional view showing a state after the safety valve of the battery according to one embodiment of the present invention has been activated. [Figure 8] FIG. 8 is a schematic cross-sectional view showing a state after the safety valve of the battery according to one embodiment of the present invention has been activated. [Figure 9] FIG. 9 is a schematic perspective view of an exterior body of a battery according to one embodiment of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view of a safety valve of a battery according to one embodiment of the present invention. [Figure 11] FIG. 11 is a schematic cross-sectional view showing a state after the safety valve of the battery according to one embodiment of the present invention has been activated. [Figure 12] FIG. 12 is a schematic cross-sectional view showing a conventional structure of a safety valve. [Figure 13] FIG. 13 is a schematic cross-sectional view showing a conventional structure of a safety valve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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, duplicated explanations of substantially identical matters may be omitted, and only the differences may be described. In particular, similar effects due to similar configurations may not be mentioned sequentially for each embodiment.

[0011] In addition, 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)" and "inside (or inner, internal or inner circumference)" and their derivative terms should be understood to refer to the direction as described or illustrated. Similarly, "on" an element includes not only the case of contacting the upper surface of the element, but also the case of not contacting the upper surface of the element. In other words, "on" an element includes not only the position above the element, i.e., the position above the element through another object, or the position above the element with a space therebetween, but also the position directly above the element. In addition, "on" does not necessarily mean the upper side in the vertical direction. "On" merely indicates the relative positional relationship of a certain element. In other words, unless otherwise expressly described, the invention does not need to be limited to only a specific direction, orientation, shape, etc. The same applies to terms such as "provided," "disposed," "connected," and "attached," and their derived terms, and unless otherwise explicitly stated, they are not limited to a direct manner, but may also refer to a manner in which other elements, such as intervening objects, are involved.

[0012] [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 essentially only be discharged. Note that the term "secondary battery" is not overly limited to its name, and may also include, for example, "electricity storage devices."

[0013] For convenience of explanation, the battery according to the present invention will be explained below mainly taking a secondary battery as an example.

[0014] The secondary battery according to the present invention includes a battery assembly including a positive electrode, a negative electrode, and a separator. In the secondary battery according to the present invention, the battery assembly may have a wound structure (hereinafter, also referred to as a "wound electrode body" or a "wound structure") in which the positive electrode, the negative electrode, and the separator are wound into a roll shape. FIG. 1 shows an example of the external appearance of a secondary battery 1000, and FIG. 2 shows an example of the internal structure. As shown in the figure, a battery assembly 10 is accommodated inside an exterior body 50. In the example shown in FIG. 2, the battery assembly 10 has a configuration in which a positive electrode 11, a negative electrode 12, and a separator 13 arranged between the positive electrode 11 and the negative electrode 12 are wound. In the secondary battery 1000, such a battery assembly 10 is enclosed in an exterior body 50 together with an electrolyte (e.g., a non-aqueous electrolyte).

[0015] 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 battery 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.

[0016] 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 battery 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.

[0017] 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, that is, 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 that can absorb and release 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 layers that can absorb and release lithium ions as the positive electrode and the negative electrode.

[0018] 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.

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

[0020] The lithium-containing composite oxide having a layered rock salt type crystal structure may be, for example, a compound represented by each of the following formulas (1) to (3). Li a Mn (1-b-c) Ni b M11 c O (2-d) F e ···(1) (M11 is at least one of cobalt (Co), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W). a to e satisfy 0.8 ≦ a ≦ 1.2, 0 < b < 0.5, 0 ≦ c ≦ 0.5, (b + c) < 1, -0.1 ≦ d ≦ 0.2, and 0 ≦ e ≦ 0.1. However, the composition of lithium varies depending on the charge 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 LiCo 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 (M0.65 Ni 0.22 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.

[0021] 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.

[0022] 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.

[0023] 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.)

[0024] 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.

[0025] The positive electrode layer may contain a binder. In addition, in order to facilitate the transfer of electrons that promote the battery reaction, the positive electrode layer may contain a positive electrode conductive agent. The binder of the positive electrode may contain, for example, any one or more of synthetic rubber and polymer compounds. The synthetic rubber is, for example, styrene butadiene rubber, fluorine rubber, and ethylene propylene diene. The polymer compound is, for example, polyvinylidene fluoride and polyimide. The positive electrode conductive agent may contain, for example, any one or more of carbon materials. The carbon material may be, for example, 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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 of them in a phase. 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 (Zn), hafnium (Hf), zirconium, yttrium (Y), palladium (Pd) and / or platinum (Pt). In a preferred embodiment, the metal element is silicon and tin. This is because these metal elements have excellent lithium absorption and desorption capabilities, and therefore a higher energy density can be easily obtained. The material containing silicon as a constituent element may be silicon alone, a silicon alloy, a silicon compound, or two or more selected from them, or may be a material containing at least one or two or more phases of them in at least 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 mentioned. 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 containing a second constituent element and a third constituent element together with tin as the first constituent element (tin-containing material). The second constituent element may be, for example, any one or more of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, zirconium, niobium, molybdenum, silver, indium, cesium (Ce), hafnium (Hf), tantalum, tungsten, bismuth, and silicon. The third constituent element may be, for example, any one or more of boron, carbon, aluminum, and phosphorus. This is because high battery capacity, excellent cycle characteristics, etc. are easily obtained by these elements. Among them, the tin-containing material may be a material containing tin, cobalt, and carbon as constituent elements (tin-cobalt-carbon-containing material). This is because high energy density is easily obtained by these materials. In the tin-cobalt-carbon-containing material, at least a part of the carbon as 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 whose constituent elements are only tin, cobalt, and carbon (SnCoC). 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 containing tin, cobalt, iron, and carbon as constituent elements (tin-cobalt-iron-carbon-containing material) may also be used.

[0030] In addition, the negative electrode material may be, for example, one or more of metal oxides and polymer compounds. The metal oxide may be, for example, iron oxide, ruthenium oxide, molybdenum oxide, etc. The polymer compound may be, for example, polyacetylene, polyaniline, polypyrrole, etc.

[0031] 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 the group consisting of carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, carbon fibers such as graphite, carbon nanotubes, and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum, and silver, and polyphenylene derivatives can be mentioned. The negative electrode material layer may contain a component resulting from a thickener component (e.g., carboxymethyl cellulose) used during battery production.

[0032] 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.

[0033] 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.

[0034] 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 porous films. Examples of synthetic resins 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. This improves the adhesion of the separator to the positive electrode and improves the adhesion of the separator to the negative electrode, making it easier to suppress distortion of the wound electrode body. The polymer compound layer may include, for example, one or more of a polymer compound such as polyvinylidene fluoride. This makes it easier to have excellent physical strength and to be 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.

[0035] In the secondary battery of the present invention, a battery assembly including a positive electrode, a negative electrode, and a separator may be enclosed in an exterior body together with an electrolyte, which may be a non-aqueous electrolytic solution.

[0036] Typically, the electrolyte contains a solvent and an electrolyte salt. The electrolyte may further contain any one or more of other materials such as additives. In a preferred embodiment, the separator is impregnated with the electrolyte, and the positive electrode and / or the negative electrode may also be impregnated with the electrolyte.

[0037] 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 makes it easier 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 makes it easier to improve the chemical stability of the electrolyte. The "unsaturated cyclic carbonate" referred to here is 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 "halogenated carbonate" is 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.The dinitrile compound is, for example, a compound represented by NC-R1-CN (R1 is either an alkylene group or an arylene group). The dinitrile compound may be, for example, succinonitrile (NC-C2H4-CN), glutaronitrile (NC-C3H6-CN), adiponitrile (NC-C4H8-CN), and phthalonitrile (NC-C6H4-CN). The diisocyanate compound is, for example, a compound represented by 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).

[0038] 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.

[0039] The exterior body used in the secondary battery corresponds to a battery exterior body, which is a member that encases a battery assembly in which a positive electrode, a negative electrode, and a separator are laminated. Such an exterior body can also be called, for example, a "battery can." The exterior body may have, for example, a hollow structure with one end closed and an opening at the other end. The opening may be a through hole formed at one end of the exterior body. The structure of the exterior body with such an opening can also be interpreted as a structure with an open end with one end open. The opening of the exterior body may be provided with a safety valve. Although this is merely an example, the opening of the exterior body may be provided with a safety valve together with a battery lid, a thermosensitive resistor, and the like.

[0040] [Knowledge that formed the basis of this disclosure] When a secondary battery is overcharged or when the battery becomes abnormally hot due to thermal energy applied from the outside, such as by being exposed to high temperature conditions, an undesired chemical reaction may proceed inside the exterior body, generating gas such as carbon dioxide. In this case, if the generated gas increases the pressure inside the exterior body (i.e., the internal pressure of the exterior body), the exterior body may eventually burst. In a conventional safety valve, when the internal pressure of the exterior body increases, a configuration is considered in which a current path of the battery is interrupted and gas is vented by cutting off and opening a part of the component of the safety valve. In such a safety valve, the current path is cut off by utilizing a force acting from the inside of the exterior body toward the outside due to the increased internal pressure, and then a part of the component is cleaved to vent the gas.

[0041] The inventors of the present application found that the function of the safety valve that is required with priority may differ depending on the state of the battery, and conducted extensive research into a safety valve that can function appropriately regardless of the state of the battery. Specifically, they found that the function that is required with priority for the safety valve may differ between an overcharged state and an abnormally high temperature state in which the battery is at a high temperature.

[0042] In an overcharged state, the reaction that generates undesired gas can be stopped by interrupting the current path, so it is required that the current path interruption mechanism functions. On the other hand, in an abnormally high temperature state, gas is generated inside the exterior body due to high temperature, so the internal pressure of the exterior body may still increase even if the current path is interrupted. Therefore, rather than interrupting the current, it is required to release a large amount of gas to the outside at an early stage. In a battery using a conventional safety valve, the internal pressure required from the interruption of the current path to the cleavage is relatively high, and the amount of gas that can leak from the cleavage part is relatively small, so that gas release is insufficient in an abnormally high temperature state, and there is a risk of the battery exploding.

[0043] In response to the above-mentioned problems, the inventors of the present application attempted to solve the problems by providing a battery that includes a current path interruption mechanism for dealing with an overcharged state, as well as a gas venting mechanism for dealing with an abnormally high temperature state. As a result, they have invented a more reliable battery that can suppress or avoid battery explosion in both an overcharged state and an abnormally high temperature state. The characteristics of the battery of the present invention will be described in detail below.

[0044] [Characteristics of the Battery of the Present Invention] The battery of the present invention has features related to a safety mechanism provided therein. In particular, the battery of the present invention has features related to the battery's exterior body and a safety valve combined with the exterior body (particularly, its opening). For convenience of explanation, the battery of the present invention will be described below using a secondary battery as an example.

[0045] 1 and 2 are schematic diagrams showing the appearance and cross-sectional view of the battery of the present invention. As shown in the figures, the battery 1000 of the present invention may be a cylindrical battery (e.g., a cylindrical nonaqueous secondary battery). In other words, the battery of the present invention may have a cylindrical case, i.e., a cylindrical exterior body 50. The safety valve 100 may be provided at the cylindrical end of the battery 1000 (particularly, on the opening 56 side of the exterior body). 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. FIG. 5 is a schematic diagram showing the safety valve 100 provided in the battery 1000 in a normal state as an enlarged cross-sectional view. The "normal state" refers to a state in which the pressure inside the battery, i.e., the internal pressure of the exterior body 50, is within a normal range and the safety mechanism is not activated.

[0046] In the battery 1000 of the present invention, the exterior body 50 includes a cylindrical portion 52. The exterior body 50 further includes a support portion 54 provided at one end of the cylindrical portion 52 so as to protrude inward from a body portion 522 of the cylindrical portion 52, and an opening portion 56 surrounded by the support portion 54. That is, the support portion 54 may protrude from the cylindrical portion 52 toward the inner periphery of the cylindrical portion 52. This structure can also be interpreted as a structure in which the support portion 54 extends so as to protrude from the edge of the cylindrical portion 52 toward the battery axis P. The opening portion 56 corresponds to an opening region surrounded by the support portion 54. The safety valve 100 provided in the battery of the present invention is disposed on the support portion 54 so as to close the opening portion 56 of the exterior body. In other words, the support portion 54 supports the safety valve 100 disposed so as to close the opening portion 56. The safety valve 100 is positioned on the outer side of the exterior body 50 so as to cover the opening portion 56. In other words, the safety valve 100 is positioned outside the support portion 54 in the battery axial direction.

[0047] In the battery of the present invention, a thermoplastic resin layer 140 is disposed between the safety valve 100 and the support portion 54. The safety valve 100 and the support portion 54 are fixed via the thermoplastic resin layer 140. The safety valve 100 may be adhered and fixed to the exterior body 50 by the thermoplastic resin layer 140 disposed on the support portion 54. In other words, the thermoplastic resin layer 140 is disposed between the safety valve 100 and the support portion 54, and can contribute to fixing the safety valve 100 on the support portion 54.

[0048] The thermoplastic resin layer 140 disposed between the support part 54 of the exterior body and the safety valve 100 softens in a high temperature state. The softening of the thermoplastic resin layer 140 may reduce the force that fixes (or bonds) the support part 54 and the safety valve 100. When the battery is in an abnormally high temperature state and the internal pressure of the exterior body 50 increases due to the gas generated inside the exterior body 50, the safety valve 100 receives a force from the inside of the exterior body 50 toward the outside due to the pressure. Due to the force, the fixation (bonding) between the support part 54 and the safety valve 100 via the thermoplastic resin layer 140 softened by the high temperature is released, and the gas inside the exterior body 50 is released to the outside from between the support part 54 and the safety valve 100. As a result, the internal pressure that has risen due to the abnormally high temperature state can be suitably released, and a battery that can suitably release the internal pressure of the battery not only in an overcharged state but also in an abnormally high temperature state can be obtained.

[0049] Furthermore, in the battery of the present invention, gas can be released from the opening 56 by at least partially detaching the safety valve 100 from the exterior body 50. Therefore, in comparison with the case where gas is released from the cleaved portion of the safety valve 100, the battery of the present invention can release gas from a larger opening area. Therefore, gas within the exterior body 50 can be released more efficiently, and the internal pressure of the exterior body 50 can be released more quickly, which may favorably prevent the battery from exploding.

[0050] The battery of the present invention will be described in detail below with reference to the drawings. The safety valve 100 of the battery is composed of at least a first metal member 110, a second metal member 130, and an insulating member 120 located therebetween. As a specific example embodiment, the first metal member 110 may correspond to a safety cover, and the second metal member 130 may correspond to a stripper disk.

[0051] 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. When viewed along the axial direction of the cylindrical shape of the battery, the safety cover 110 as the first metal member is positioned relatively outside the battery (i.e., the side farther from the battery assembly such as a wound structure), while the stripper disk 130 as the second metal member is positioned relatively inside the battery (i.e., the side closer to the battery assembly such as a wound structure). An insulating member 120 is interposed between the safety cover 110 and the stripper disk 130. In this specification, the "axial direction of the cylindrical battery" corresponds to the central axis of the cylindrical exterior body 50, and is also referred to as the "battery axis" in this specification. In other words, the "battery axis" may refer to an axis passing through the center of the exterior body 50 in a plan view of the battery viewed from the end side of the exterior body 50 on which the safety valve 100 is disposed. For example, the "battery axis" may correspond to an axis that passes through the center of the tubular portion 52 of the exterior body 50 and extends in a direction perpendicular to the end face of the exterior body (particularly the end face on a virtual plane). For example, the "battery axis" may also be interpreted as 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.

[0052] The safety valve 100 has at least a mechanism that serves as a battery terminal (i.e., an external terminal of the positive or negative electrode) and can be displaced in response to excessive internal pressure of the battery as a safety mechanism. More specifically, the safety valve 100 has at least a safety cover 110 and a stripper disk 130 that can be displaced in response to excessive internal pressure of the battery, and an insulating member 120 therebetween as components. Such a safety valve 100 is provided at one end of the exterior body 50, particularly at the end having the opening 56. The safety valve 100 may further include a top cover 150. The top cover 150 may be provided on the outer side of the battery relative to the safety cover 110 provided as the first metal member. Each member that constitutes the safety valve 100 will be described in more detail below.

[0053] (Safety cover) The safety cover 110 provided as the first metal member mainly closes the opening 56 of the exterior body and corresponds to a displaceable member that is deformable and / or rupturable in response to the internal pressure of the exterior body 50. As described above, the internal pressure of the exterior body 50 may increase undesirably due to gases such as carbon dioxide that are generated when the battery enters an abnormal state. The safety cover 110 may be deformable and / or rupturable in response to such an increase in internal pressure.

[0054] The safety cover 110 is a conductive member, for example a metal member, and may include, for example, one or more of metal materials such as aluminum (e.g., aluminum alloys such as A1050, A3203, and A5052), titanium, platinum, and gold.

[0055] The planar shape of the safety cover 110, that is, the outer contour shape in a plan view seen along the battery axis P direction (also referred to as the "planar outer contour shape") is not particularly limited, and may be, for example, a circle, a polygon, or other shapes. In this specification, the "circle" refers to, for example, a perfect circle (correct circle), an ellipse, and an approximate circle. The approximate circle is, for example, a general term for a shape in which a perfect circle is partially or entirely distorted. The "polygon" refers to, for example, a triangle, a square, a pentagon, and a hexagon. The "other shape" refers to, for example, a shape other than a circle whose contour 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. This definition is the same hereinafter. In the illustrated exemplary embodiment, the planar outer contour shape of the safety cover 110 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. Although this is merely an example, the safety cover 110 may have a substantially constant thickness, except for the groove portion 112 and the like provided in the safety cover 110.

[0057] (Insulating material) 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 an annular, ring, or ring shape, the insulating member 120 may have a central region that forms a hollow or an opening region 122. The outer contour shape of such an insulating member 120 in a plan view is not particularly limited, but may be similar to the outer contour shape of the safety cover 110 in a plan view, or may be similar to the outer contour shape of the stripper disk 130 in a plan view. For example, the outer contour shape in a plan view can be a circle. Note that the annular, ring, or ring shape of such an insulating member 120 may be a continuous shape as a whole member, or may be locally divided and / or cut out.

[0058] The insulating member 120 may be, for example, generally flat. In other words, the insulating member 120 may have a shape that extends on the same plane. As an example, the insulating member 120 may have a substantially constant thickness between the safety cover 110 and the stripper disk 130.

[0059] The insulating member 120 is a member having insulating properties. Therefore, electrical conduction through the insulating member 120 is preferably prevented. In this specification, "insulation" may have the insulating properties of a general insulator and therefore the electrical resistivity of a general insulator. As a mere example, the insulating member 120 may have a resistivity of 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).

[0060] In a preferred embodiment, the insulating member 120 interposed between the safety cover 110 and the stripper disk 130 is bonded to them. In other words, the insulating member 120 may be interposed between the safety cover 110 and the stripper disk 130 as an adhesive layer. Preferably, the insulating member 120 may be interposed between the safety cover 110 and the stripper disk 130 so that an opening region 122 of the insulating member is positioned in a region including the battery axis P. The opening region 122 is positioned at a location corresponding to the central region 110X of the safety cover. The planar shape of the opening region 122 is not particularly limited, and may be the same as the planar outer contour shape of the safety cover 110, for example. In the illustrated exemplary embodiment, the planar shape of the opening region 122 is circular.

[0061] The insulating member 120 is preferably made of an insulating resin material. This is because the resin material can more suitably contribute to the adhesion between the safety cover 110 and the stripper disk 130 while ensuring the insulation, and thus contributes to the realization of a thinner safety valve. When the insulating member 120 is made of a resin material, the insulating member 120 may be made of, for example, a thermosetting resin, a thermoplastic resin, and / or a UV-curable resin. When particular importance is placed on the viewpoint of adhesiveness, the insulating member 120 may be a member containing a resin adhesive exhibiting insulating properties. 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.

[0062] (Stripper disc) The stripper disk 130 provided as the second metal member is disposed inside the battery relative to the safety cover 110 via the insulating member 120. The stripper disk 130 corresponds to a member that contributes to breaking the electrical connection between the battery assembly disposed inside the exterior body 50 and the safety cover 110 and / or the top cover 150.

[0063] The stripper disk 130 is provided with a groove 132 for interrupting a current path in the event of an abnormality in the battery. The groove 132 may be provided, for example, so as to surround the battery axis P. In other words, the groove 132 may be an annular groove formed so as to surround the center of the opening 56. The groove 132 may have a continuous annular shape surrounding the battery axis P, or may have an intermittent annular shape. Alternatively, instead of the groove 132 (or together with the groove 132), linear through holes may be intermittently provided around the battery axis P. The groove 132 may be a groove having an opening toward the outside of the battery axis P. In other words, the groove 132 may have a groove opening on a surface of the second metal member that faces relatively toward the outside of the battery in the direction of the battery axis P.

[0064] The stripper disk 130 is a conductive member, for example a metal member. For example, the safety cover 110 may contain one or more of metal materials such as aluminum (for example, aluminum alloys such as A1050, A3203, and A5052), titanium, platinum, and gold. The material of the stripper disk 130 may be the same as that of the safety cover 110, or may be a different material from that of the safety cover 110.

[0065] The outer contour shape in a plan view of the stripper disk 130 is not particularly limited, and may be, for example, a circle, a polygon, or other shape. The outer contour shape in a plan view of the stripper disk 130 may be similar to the outer contour shape in a plan view of the safety cover 110. In the illustrated exemplary embodiment, the outer contour shape in a plan view of the safety cover 110 is a circle.

[0066] The stripper disk 130 may be, for example, flat as a whole. That is, the stripper disk 130 may have a shape extending on the same plane. For example, the stripper disk 130 may have a substantially constant thickness except for the grooves 132 and the like provided therein. The central region 130X of the stripper disk 130 may be relatively thicker than the other regions in order to contribute to the connection with the safety cover 110. In other words, the stripper disk 130 may have a plate-like shape as a whole, but the thickness of the central part of the region including the battery axis P may be relatively large.

[0067] In the safety valve 100, the safety cover 110 and the stripper disk 130 are integrated with each other by the insulating member 120 interposed therebetween, and 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 130X of the stripper disk 130 so as to straddle the insulating member 120. More specifically, as shown in FIG. 5, the central region 110X of the safety cover 110 and the central region 130X of the stripper disk 130 may be directly connected to each other through the opening region 122 of the insulating member.

[0068] (Top cover) As described above, the safety valve 100 may further include a top cover 150. That is, the top cover 150 may be provided on the relatively outer side of the safety cover 110 provided as the first metal member. That is, the top cover 150 may be disposed on the relatively outer side of the battery than the safety cover in the direction of the battery axis P. The top cover 150 is preferably electrically connected to the safety cover 110. The top cover 150 may be provided with a plurality of openings 154. The plurality of openings 154 mainly correspond to exhaust ports that contribute to the passage or release of gas to the outside of the exterior body when the gas inside the exterior body leaks from the cleaved portion of the safety cover 110.

[0069] The top cover 150 is a conductive member, and may be, for example, a metal member. For example, the top cover 150 may include any one or more of metal materials such as aluminum (e.g., aluminum alloys such as A1050, A3203, and A5052), titanium, platinum, and gold.

[0070] The top cover 150 may function as a terminal of the battery. For example, the top cover 150 may function as a positive terminal of the battery, and the exterior body 50 may function as a negative terminal. Therefore, the top cover 150 and the exterior body 50 may be insulated from each other.

[0071] A conductive member 15 extending from the battery assembly is connected to the safety valve 100. More specifically, the conductive member 15 is connected to the stripper disk 130 of the safety valve. In particular, the conductive member 15 may be connected to a non-central region 130Y, which is an area on the outer periphery side of the groove 132 of the stripper disk. The "non-central region" refers to an area other than the central region 130X on the inner periphery side of the groove 132, and can also be called the "outer periphery region." The conductive member 15 is electrically connected to the battery assembly (particularly, either one of the positive electrode or the negative electrode), and contributes to the electrical connection between the battery assembly and the safety valve 100 (particularly, the stripper disk 130). In the safety valve 100, the stripper disk 130 is electrically connected to the safety cover 110 via the central region 130X. The safety cover 110 is also electrically connected to a top cover 150 that constitutes an external terminal of the battery. Therefore, the battery assembly, such as the wound structure, is electrically connected to the external terminals of the battery via the conductive members 15 .

[0072] The conductive member 15 may be a conductive member containing a metal, and may preferably be a metal member having an elongated shape. For example, the conductive member 15 may be made of an electrode current collector of a battery assembly, or may be a current collector lead provided on the battery assembly (particularly, its electrode). When the conductive member 15 is made of an electrode current collector, the conductive member 15 may be made of a portion of the electrode current collector on which no electrode material is provided. When the conductive member 15 is a current collector lead, the conductive member 15 may be made of a metal member having a thin-walled shape and / or an elongated shape and may be connected to an electrode. In the present invention, the conductive member 15 that electrically connects the battery assembly and the electrode terminal to each other may also be called a "tab". The conductive member 15 used in the secondary battery is preferably flexible, and may be provided in a bent and / or curved shape.

[0073] In the safety valve 100 of the battery of the present invention, the safety cover 110, insulating member 120, and stripper disk 130, which are the first metal member and the second metal member, respectively, are combined so as to be stacked on top of each other. More specifically, as shown in Fig. 5, the safety cover 110 and insulating member 120 provided as the first metal member are arranged so as to be stacked on top of each other, and the insulating member 120 and the stripper disk 130 provided as the second metal member are arranged so as to be stacked on top of each other. Furthermore, the top cover 150 is arranged so as to be stacked on the safety cover 110.

[0074] Such a safety valve assembly is disposed outside the exterior body 50 so as to close an opening 56 provided at one end of the exterior body 50. The exterior body 50 of the battery of the present invention includes a tubular portion 52 and a support portion 54 that protrudes inward from a body portion 522 (e.g., an edge 524 of the body portion) of the tubular portion 52 at one end of the tubular portion 52. An opening 56 surrounded by the support portion 54 is provided on the end face of the exterior body that includes the support portion 54. That is, the exterior body 50 includes an opening 56 at one end, and the support portion 54 is provided around the opening 56 so as to protrude from the tubular portion 52 of the exterior body toward the battery axis P. The support portion 54 is a portion that protrudes toward the inner periphery of the tubular portion 52 at the edge 524 of the tubular portion 52 of the exterior body, and can also be interpreted as a portion that forms the end face of the exterior body 50, and can also be referred to as a "protruding portion" or an "end face protruding portion".

[0075] The support portion 54 may be a separate member from the tubular portion 52 (see FIG. 3). That is, the support portion 54 has an outer contour shape in plan view that corresponds to the shape of the edge 524 of the tubular portion 52 in plan view, and may be combined with the edge 524 of the tubular portion 52 by using a welding method or the like. A through hole is formed in the area surrounded by the support portion, and the through hole corresponds to the opening 56 of the exterior body. A battery having an exterior body with such a structure can be, for example, a battery having a structure without a beading portion.

[0076] In a conventional safety valve structure, a safety valve is disposed in an exterior body 50 having a beading portion 58 formed around the outer periphery of a body portion 522 of a tubular portion 52 of the exterior body. The "beading portion" refers to a portion in the body portion 522 of the tubular portion 52 that is constricted toward the battery axis P side. In other words, the "beading portion" is a portion that is constricted so as to be convex toward the inside of the exterior body 50, and can also be called a "constricted portion" or a "narrowed portion". In a conventional battery having an exterior body having a beading portion 58, a support member such as a gasket is disposed in the beading portion 58, and the safety valve is held inside the exterior body via the gasket portion (FIG. 12). In other words, the conventional safety valve is disposed inside the exterior body having the beading portion 58.

[0077] In contrast, according to the present invention, since the safety valve can be disposed on the outer side of the exterior body 50, the safety valve can be disposed without depending on the beading portion. Therefore, the safety valve can be disposed not only in the exterior body having the beading portion, but also in the exterior body not having the beading portion. In the exterior body 50 not having the beading portion, the inner diameter dimension of the exterior body 50 may be substantially constant along the battery axis P. Therefore, the exterior body 50 can secure a larger internal space in which the battery assembly can be disposed, compared with the exterior body 50' having the beading portion 58 (see Figs. 9 and 10). In other words, by using an exterior body not having a beading portion, a battery with a higher energy density can be provided. According to the present invention, since the safety valve can be suitably disposed in the exterior body not having the beading portion, a battery having a high energy density and excellent safety can be obtained.

[0078] On the other hand, the exterior body may have a beading portion. FIG. 9 is an exploded perspective view of an exterior body 50' in one embodiment of the present invention. FIG. 10 is a perspective partial cross-sectional view of a battery including the exterior body 50'. The support portion 54 may be a portion continuing from the tubular portion 52. That is, the support portion 54 and the tubular portion 52 may be an integrated body. More specifically, the support portion 54 may correspond to a portion in which a member forming the tubular portion 52 is bent toward the battery axis P at the edge 524 of the tubular portion 52 and protrudes toward the inner periphery of the tubular portion 52. In one embodiment, the support portion 54 may correspond to a protruding surface formed on the edge 524 of the exterior body by crimping one open end of the tubular portion 52. According to the present invention, the safety valve can be suitably arranged regardless of the presence or absence of a beading portion.

[0079] The cylindrical portion 52 and the supporting portion 54 of the exterior body may both be conductive members. That is, the cylindrical portion 52 and the supporting portion 54 may be electrically connected to each other. For example, the cylindrical portion 52 and the supporting portion 54 may be made of one or more metal materials such as iron, aluminum, stainless steel, and alloys thereof. The cylindrical portion 52 and the supporting portion 54 may be made of the same material or different materials. The surfaces of the cylindrical portion 52 and / or the supporting portion 54 may be plated with one or more metal materials such as nickel.

[0080] In the battery of the present invention, the safety valve 100 is disposed on the support portion 54 of the exterior body. That is, the safety valve 100 is positioned on the outer side of the battery than the support portion 54. This structure can also be interpreted as the safety valve 100 being disposed on the outer side than the support portion 54 with respect to the direction of the battery axis P. More specifically, the safety valve 100 may be bonded to the outer main surface 54a, which is located relatively on the outer side of the exterior body 50, of the two main surfaces extending in the radial direction. A thermoplastic resin layer 140 is interposed between the safety valve 100 and the support portion 54. The thermoplastic resin layer 140 may be disposed on the outer main surface 54a of the support portion and fix the safety valve 100 on the support portion 54. The planar shape of the thermoplastic resin layer 140 may be a ring shape along the opening end 56a of the opening. Therefore, the thermoplastic resin layer 140 may extend around the opening end 56a of the opening so as to surround the opening 56.

[0081] The thermoplastic resin layer 140 interposed between the safety valve 100 and the support portion 54 may be bonded to them. In other words, the thermoplastic resin layer 140 may be interposed between the safety valve 100 and the support portion 54 as an adhesive layer. Therefore, the safety valve 100 and the support portion 54 may be bonded to each other via the thermoplastic resin layer 140. Such a thermoplastic resin layer 140 may also be called a "thermoplastic resin adhesive layer" or the like.

[0082] As described above, the top cover 150 of the safety valve is electrically connected to one of the positive and negative electrodes of the battery assembly via the safety cover 110, the stripper disk 130, and the conductive member 15. On the other hand, the other electrode is electrically connected to the exterior body 50. For example, the top cover 150 of the safety valve may function as a positive terminal of the battery, and the exterior body 50 including the cylindrical portion 52 and the support portion 54 may function as a negative terminal. Therefore, the conductive members of the safety valve 100 (particularly, the top cover 150, the safety cover 110, and the stripper disk 130) may be insulated from the exterior body 50. The exterior body 50 and the safety valve 100 may be insulated from each other by the insulating thermoplastic resin layer 140 interposed between them. In other words, the exterior body 50 and the safety valve 100 may be insulated from each other by the thermoplastic resin layer 140 interposed between the support portion 54 and the safety valve 100. That is, the thermoplastic resin layer 140 can contribute to insulating the safety valve 100 from the support portion 54 (exterior body) in addition to bonding the safety valve 100 to the support portion 54.

[0083] As shown in Fig. 5, in the battery of the present invention, the safety valve 100 is disposed outside the exterior body 50. Therefore, the battery of the present invention does not require a space for disposing the safety valve 100 inside the exterior body 50. Therefore, a larger battery assembly can be disposed inside the exterior body 50, and the internal volume of the electrodes can be effectively utilized. This makes it possible to further improve the energy density of the battery.

[0084] In one embodiment, the safety cover 110 includes an outer peripheral region 110Y that extends radially outward beyond the stripper disk 130. The "radial direction" refers to the radial direction of the cylindrical portion 52 of the exterior body, that is, the direction perpendicular to the battery axis P. That is, the radial dimension of the safety cover 110 may be larger than the radial dimension of the stripper disk 130 in a plan view. The support portion 54 may be bonded to the safety cover 110 of the safety valve via a thermoplastic resin layer 140. More specifically, the support portion 54 may be overlapped in the battery axis P direction with the outer peripheral region 110Y of the safety cover 110 that extends radially outward beyond the stripper disk 130, and may be bonded to each other via a thermoplastic resin layer 140. As described above, the stripper disk 130 is located relatively inward in the battery axis P direction from the safety cover 110. Therefore, by adopting a structure in which the support portion 54 and the safety cover 110 are bonded together, the stripper disk 130 can be disposed relatively inside the exterior body 50. This makes it possible to shorten the distance between the stripper disk 130 and the battery assembly disposed inside the exterior body, thereby reducing the space between the safety valve 100 and the battery assembly and enabling the battery to be made smaller.

[0085] Next, the operating mechanism of the safety mechanism of the battery of the present invention will be described with reference to the drawings. Figures 6 and 7 are schematic diagrams illustrating the safety mechanism caused by the breakage and / or rupture of the stripper disk 130 and the safety cover 110 constituting the safety valve 100.

[0086] For example, when gas is generated inside the exterior body 50 due to a side reaction such as a decomposition reaction of the electrolyte solution caused by overcharging, the gas accumulates inside the exterior body 50, and the internal pressure of the exterior body 50 rises. If the internal pressure of the exterior body 50 continues to rise, the stripper disk 130 and the safety cover 110 are affected by the rise in internal pressure. If the internal pressure of the exterior body 50 exceeds a predetermined pressure, as shown in FIG. 6, the central region 110X of the safety cover is pushed up toward the outside of the battery along the direction of the battery axis P and displaced. With this displacement, the central region 130X of the stripper disk 130 is also pushed up in the displacement direction and breaks starting from the groove portion 132 provided in the stripper disk 130. In this specification, "break" means that the connection is completely cut off. As a result, the stripper disk 130 is divided into the central region 130X on the inner periphery side of the groove portion 132 and the non-central region 130Y on the outer periphery side of the groove portion 132. More specifically, the stripper disk 130 is divided into a central region 130X connected to the safety cover 110 and a non-central region 130Y connected to the conductive member 15. As can be seen from the form shown in FIG. 6, such division physically separates the safety cover 110 and the non-central region 130Y of the stripper disk from each other. Thus, the electrical connection between the top cover 150 and the battery assembly is cut off, and the current path between the top cover 150 and the battery assembly is interrupted. In this way, it is possible to cut off the current of the battery when the internal pressure abnormally increases.

[0087] After the above-mentioned cutoff mechanism is activated, if the displacement of the safety cover 110 due to the internal pressure continues, the safety cover 110 may be torn or broken starting from the groove 132 provided in the safety cover 110 (see FIG. 7). In this specification, "torn" includes a form in which at least a part is separated while a part is continuous. That is, the safety cover 110 may not be completely separated between the central region 110X on the inner periphery side of the groove 112 and the non-central region 110Y on the outer periphery side of the groove 112, or may be completely separated. When the safety cover 110 is torn, the gas inside the exterior body 50 is released to the outside from the torn part, and the internal pressure is reduced. In such a case, the gas release path via the multiple openings 154 formed in the top cover 150 is opened, and the gas can be released to the outside of the battery via the open part. In one embodiment, the stripper disk 130 also includes an opening 134 through which gas within the outer casing 50 may be vented to the outside.

[0088] As described above, factors that cause the pressure inside the battery to rise include the battery being in an overcharged state and the battery being in an abnormally high temperature state. The battery of the present invention has a structure that can suitably release the internal pressure of the battery not only when the battery is in an overcharged state but also when the battery is in an abnormally high temperature state. FIG. 8 is a cross-sectional view that shows a battery of the present invention in an abnormally high temperature state. FIG. 11 is a cross-sectional view that shows a battery of the present invention in an abnormally high temperature state, in which the exterior body has a beading portion. In the present invention, the "abnormally high temperature state" means a state in which the temperature inside the battery rises and gas is abnormally generated inside the battery. For example, the "abnormally high temperature state" may be a state in which the temperature of the outer surface of the battery is 100° C. or higher. In the abnormally high temperature state, the thermoplastic resin layer 140 that contributes to the adhesion between the support part 54 and the safety valve 100 softens due to the high temperature. This reduces the adhesive force between the support part 54 and the safety valve 100 by the thermoplastic resin layer 140. On the other hand, when the internal pressure of the exterior body 50 increases due to gas generated inside the exterior body 50 due to an abnormally high temperature state, a force pushing toward the outside of the battery in the direction of the battery axis P may act on the safety valve 100. When the pushing force acts on the safety valve 100 in a state in which the adhesive strength of the thermoplastic resin layer 140 is reduced, the safety valve 100 may be detached from the support part 54 of the exterior body, and gas may be released to the outside from the opening part 56 of the exterior body. This allows the internal pressure of the exterior body 50 to be suitably reduced. In this way, the internal pressure of the battery can be released when the internal pressure of the exterior body 50 increases due to an abnormally high temperature state. Such a gas venting mechanism caused by high temperature can also be interpreted as a gas venting mechanism involving thermal cleavage between the safety valve 100 and the support part 54, for example, and is hereinafter also referred to simply as a "thermal cleavage mechanism".

[0089] As described above, the battery of the present invention includes a current interruption mechanism associated with the rupture of the stripper disk 130, a gas venting mechanism associated with the cleavage of the safety cover 110 of the safety valve, and also a gas venting mechanism associated with the softening of the thermoplastic resin layer 140 in an abnormally high temperature state (thermal cleavage mechanism). In the gas venting mechanism via the safety cover 110, gas venting is performed via the rupture of the stripper disk 130 and the cleavage of the safety cover 110, whereas in the thermal cleavage mechanism, gas venting can be performed immediately in an abnormally high temperature state by peeling off the adhesive portion between the exterior body 50 and the safety valve 100 via the thermoplastic resin layer 140.

[0090] Furthermore, according to the structure of the present invention, the safety valve 100 is disposed so as to overlap the support portion 54 in the direction of the battery axis P, and therefore is not subjected to pressure from the radial direction as shown in the conventional crimping structure (FIG. 12). This allows the safety valve 100 to be easily peeled off from the support portion 54 when the internal pressure of the exterior body 50 increases. Furthermore, since the safety valve 100 is located outside the support portion 54 in the direction of the battery axis P, when the internal pressure of the exterior body 50 increases, the safety valve 100 can be suitably peeled off from the support portion 54 without being hindered by other members.

[0091] The thermoplastic resin layer 140 contributes to sealing between the support portion 54 and the safety valve 100 in a non-abnormally high temperature state including a normal state (for example, a state in which the battery is in a temperature range of 25° C. or more and less than 100° C.). That is, in a normal state, the exterior body 50 may be sealed by the safety valve 100 and the thermoplastic resin layer 140 interposed between the safety valve 100 and the exterior body 50. This makes it possible to break the stripper disk 130 by utilizing the internal pressure increase when the battery is in a non-abnormally high temperature state due to overcharging or the like, thereby cutting off the current path. That is, in an abnormally high temperature state, a gas venting mechanism accompanied by thermal cleavage in the thermoplastic resin layer 140 operates, whereas in an abnormal state of the battery other than the abnormally high temperature state (for example, an overcharged state), it becomes possible to operate a current path cutoff mechanism before the thermal cleavage mechanism operates.

[0092] The thermoplastic resin layer 140 disposed between the support portion 54 and the safety valve 100 contains a thermoplastic resin. In terms of resistance to the electrolyte, the thermoplastic resin layer 140 preferably contains a crystalline thermoplastic resin. For example, the thermoplastic resin layer 140 may contain at least one resin selected from super engineering plastics-based resins and polyolefin-based resins. Examples of super engineering plastic resins include polyether ether ketone (PEEK), polyamide imide (PAI), polyphenylene sulfide (PPS), polyetherimide (PEI), polyether ketone ketone (PEKK), polyethylene naphthalate (PEN), super engineering plastic polysulfone (PSU), polyether sulfone (PES), polyarylate (PAR), polyamide imide (PAI), polyimide (PI), PBI (polybenzimidazole), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), Neoflon (PFA), Fluon, Neoflon (ETFE), and polyvinylidene fluoride (PVDF). Examples of polyolefin resins include polyolefin resins such as polyethylene, polypropylene, polymethylpentene, polybutene, ethylene-propylene copolymer, ethylene-α-olefin copolymer, and propylene-α-olefin copolymer, as well as polyolefin resins such as olefin copolymer resins such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-(meth)acrylic acid (ester) copolymer, and ethylene-unsaturated carboxylic acid copolymer metal neutralized product (ionomer). When the thermoplastic resin layer 140 contains the above-mentioned thermoplastic resin, it can be suitably softened when the battery is in an abnormally high temperature state, and can thermally cleave the gap between the support portion 54 and the safety valve 100.

[0093] The melting point of the thermoplastic resin layer 140 can be 320°C or less, 340°C or less, 350°C or less, or 360°C or less. When the melting point is within the above-mentioned range, a battery that is more suitably thermally cleaved in an abnormally high temperature state and has superior safety can be obtained. When it is important that the thermoplastic resin layer 140 properly bonds and seals between the safety valve 100 and the exterior body 50 in a non-abnormally high temperature state, the melting point of the thermoplastic resin layer 140 can be, for example, 80°C or more.

[0094] As described above, factors that cause the pressure inside the battery to increase include the battery being in an overcharged state and the battery being in an abnormally high temperature state. While both of these involve abnormal generation of gas inside the exterior body 50, the inventor of the present application has found that the safety mechanisms that should be prioritized in the overcharged state and the abnormally high temperature state may be different from each other. For example, when the battery is in an overcharged state, the potential of the positive electrode increases, causing the electrolyte to be oxidized and decomposed, and a chemical reaction accompanied by the generation of gas occurs. Therefore, it is preferable to suppress the progress of the battery reaction by blocking the current path, and then release the internal pressure by degassing. On the other hand, in an abnormally high temperature state, undesirable side reactions occur in thermally unstable battery materials due to the high temperature, and gas may be generated. The abnormally high temperature state is an abnormal state caused by thermal energy applied to the battery, and is different from an abnormal state caused by electrical energy such as an overcharged state, so it may be required that the degassing mechanism operates preferentially over the current path blocking mechanism.

[0095] The battery of the present invention includes a thermal cleavage mechanism in the thermoplastic resin layer 140 between the support part 54 of the exterior body and the safety valve 100, and a rupture / cleavage mechanism of the members constituting the safety valve 100. Since all of these safety mechanisms utilize the internal pressure increased inside the exterior body 50, which of the multiple safety mechanisms functions preferentially may depend on the difference in pressure required to activate the safety mechanism. The inventors of the present application have realized a battery that can selectively activate an appropriate safety mechanism depending on the situation by controlling the pressure required to activate each safety mechanism.

[0096] The pressure Pt required for peeling of the adhesion between the safety valve 100 and the support portion 54 by the thermoplastic resin layer 140 (hereinafter also referred to as "resin fixing pressure", "resin adhesion pressure", "resin layer peeling pressure", or "thermal cracking pressure") varies according to temperature. Specifically, the thermoplastic resin layer 140 softens at high temperatures, and the adhesive strength (or fixing strength) decreases. Therefore, the resin fixing pressure Pt decreases as the temperature increases. In other words, the resin fixing pressure Pt can be higher under low temperature conditions. Based on such matters, by designing so that the resin fixing pressure in the normal state, the resin fixing pressure in the abnormally high temperature state, and the pressure required for breaking of the groove portion 132 of the stripper disk of the safety valve have an arbitrary magnitude relationship, it may be possible to realize the operation of the safety mechanism according to the state of the battery.

[0097] For example, in the normal state, the pressure Ps required for breaking of the groove portion 132 of the stripper disk of the safety valve (hereinafter also referred to as "safety valve cutoff pressure" or "stripper disk breaking pressure") is smaller than the resin fixing pressure Pt of the thermoplastic resin layer. In other words, in a non-abnormally high temperature state including the normal state, the fixing strength between the safety valve 100 and the support portion 54 by the thermoplastic resin layer 140 may be greater than the safety valve breaking pressure Ps. In the normal state, since the relationship between the safety valve cutoff pressure Ps and the resin fixing pressure Pt is Ps < Pt, in the normal state, the current path cutoff mechanism in the stripper disk 130 operates earlier than the thermal cracking mechanism in the thermoplastic resin layer 140. That is, in the normal state, before the safety valve 100 peels off from the support portion 54 in the thermoplastic resin layer 140 and gas venting is performed, the groove portion 132 of the stripper disk breaks and the current path of the battery is cutoff.

[0098] On the other hand, in the abnormally high temperature state, the resin fixing pressure Pt of the thermoplastic resin layer is smaller than the safety valve shutoff pressure Ps. In other words, in the abnormally high temperature state, the safety valve rupture pressure Ps may be greater than the fixing strength between the safety valve 100 and the support portion 54 by the thermoplastic resin layer 140. In the abnormally high temperature state, the relationship between the safety valve shutoff pressure Ps and the resin fixing pressure Pt is Ps>Pt, so that in the abnormally high temperature state, the thermal cleavage mechanism in the thermoplastic resin layer 140 operates before the current path cutoff mechanism in the stripper disk 130. That is, in the normal state, the safety valve 100 peels off from the support portion 54 in the thermoplastic resin layer 140 and gas is released before the groove portion 132 of the stripper disk breaks and the current path of the battery is cut off.

[0099] As described above, the present invention can provide a battery in which the interruption path of the current path is activated preferentially in a non-abnormally high temperature state, and the gas venting mechanism is activated preferentially in an abnormally high temperature state. In other words, the present invention can provide a more reliable battery in which a more appropriate safety mechanism can be selectively activated depending on the state of the battery.

[0100] The resin fixing pressure Pt at an arbitrary temperature can be obtained by measurement using an adhesive combination in which the support part 54 and the safety valve 100 are bonded using the thermoplastic resin layer 140. Specifically, the resin fixing pressure Pt can be obtained by applying a force from the inside side of the exterior body 50 to the safety valve 100 of the adhesive combination from the inside side to the outside side of the exterior body 50 under an arbitrary temperature condition, and measuring the pressure when the safety valve 100 peels off from the support part 54.

[0101] Furthermore, the inventors of the present application have newly discovered that the temperature dependency of the resin fixing pressure Pt of the thermoplastic resin layer 140 can be expressed by the following formula 1.

[0102] In the formula, Pt1 is the resin fixing pressure at temperature T1, Pt2 is the resin fixing pressure at temperature T2, T mis the melting point of the thermoplastic resin layer 140, and T1>T2. By measuring the resin fixing pressure Pt at a certain temperature based on the formula 1, the resin fixing pressure Pt at an arbitrary temperature can be obtained. That is, the resin fixing pressure Pt at an arbitrary temperature may be determined by measurement, or alternatively, the resin fixing pressure Pt2 at a certain predetermined temperature T2 may be determined by measurement, and the resin fixing pressure Pt1 at an arbitrary temperature T1 may be obtained based on the formula 1 using the resin fixing pressure Pt2 obtained by measurement.

[0103] The resin fixing pressure Pt at a certain temperature can be controlled by the material of the thermoplastic resin layer 140, the thickness dimension of the thermoplastic resin layer 140, the width dimension of the thermoplastic resin layer 140 in a plan view, and / or the bonding area between the support portion 54 and the safety valve 100. On the other hand, the safety valve shutoff pressure Ps can also be controlled according to the material of the stripper disk 130 and / or the shape of the groove portion 132. If it is important to make the battery fail safely in both the overcharged state and the abnormally high temperature state, it is preferable that the current path can be shut off earlier in the overcharged state and that thermal cleavage can be performed earlier in the abnormally high temperature state. According to the present invention, the material and bonding area of ​​the thermoplastic resin layer 140 can be appropriately changed so that the resin fixing pressure in the abnormally high temperature state is lower than the safety valve shutoff pressure while designing the safety valve shutoff pressure to be a lower value. This can result in a battery with better safety that can selectively activate an appropriate safety mechanism depending on the state of the battery.

[0104] (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.

[0105] 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.

[0106] When assembling a secondary battery, a positive electrode lead is connected to a positive electrode current collector by welding or the like, and a negative electrode lead is connected to a negative electrode current collector by welding 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 housed inside the exterior body together with the pair of insulating plates. In this case, one end of the positive electrode lead is connected to the safety valve by welding or the like, and one end of the negative electrode lead is connected to the exterior body by welding or the like. Next, an electrolyte is injected into the interior of the exterior body, and the electrolyte is impregnated into the wound electrode body. Finally, a support is provided on the exterior body, and a safety valve is fixed on the support via a thermoplastic resin layer. This completes a secondary battery equipped with a safety valve.

[0107] Although the embodiment of the present invention has been described above, it is merely a typical example. The present invention is not limited to this, and those skilled in the art will easily understand that various aspects are possible without departing from the scope of the present invention.

[0108] Note that the embodiment of the present disclosure as described above includes the following preferred aspects. <1> The battery includes an exterior housing that houses a battery assembly and an electrolyte, and a safety valve that is attached to the exterior housing; The battery assembly includes a positive electrode, a negative electrode, and a separator; The exterior body includes a cylindrical portion, a support portion that protrudes inward from the cylindrical portion at one end of the cylindrical portion, and an opening portion that is surrounded by the support portion, the safety valve is located at the one end of the barrel; The battery, wherein the safety valve and the support portion are fixed via a thermoplastic resin layer. <2> The support portion has an outer main surface located on the outer side of the exterior body, the relief valve is located on an outer major surface of the support; The thermoplastic resin layer is interposed between the outer main surface and the safety valve. <1> Battery. <3> In a normal state, the thermoplastic resin layer seals between the safety valve and the support portion. <1> or <2> Battery. <4> the safety valve includes a first metal member located relatively to the outside of the battery and a second metal member located relatively to the inside of the battery, The second metal member has a groove portion that can be cleaved by the internal pressure of the exterior body. <1> ~ <3> Any of the batteries. <5> the first metal member has an outer circumferential portion extending radially outward beyond the second metal member, The support portion is overlapped with the outer peripheral portion via the thermoplastic resin layer. <4> Battery. <6> the safety valve is provided in the exterior body via the thermoplastic resin layer disposed between the first metal member and the support portion. <4> or <5> Battery. <7> In a normal state, a fixing pressure of the thermoplastic resin layer is greater than a blocking pressure in the groove portion of the second metal member. <4> ~ <6> Any of the batteries. <8> In an abnormally high temperature state, the fixing pressure of the thermoplastic resin layer is lower than the blocking pressure in the groove portion of the second metal member. <4> ~ <7> Any of the batteries. <9> In an abnormally high temperature state, the fixing pressure of the thermoplastic resin layer is lower than the internal pressure of the exterior body. <1> ~ <8> Any of the batteries. <10> The melting point of the thermoplastic resin layer is 80°C or higher and 340°C or lower. <1> ~ <9> Any of the batteries. <11> The thermoplastic resin layer contains a polyolefin resin. <1> ~ <10> Any of the batteries. <12> The cylindrical portion of the exterior body has a structure that does not include a beading portion. <1> ~ <11> Any of the batteries. EXAMPLES

[0109] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples.

[0110] [Test battery] A secondary battery having the following specifications was prepared. Shape: Cylindrical (diameter: approx. 22 mm, axial length: approx. 70 mm) Positive and negative electrodes of the battery assembly: Positive and negative electrodes capable of absorbing and releasing lithium ions ·Nominal capacity: approx. 4100mAh Nominal voltage: 3.6V Safety valve: A valve configuration consisting of a top cover, a safety cover, an insulating member, and a stripper disc, in that order. (Materials of each component) Safety cover: Made of metal (metal containing aluminum) Insulation material: Resin (epoxy resin) Stripper disc: made of metal (metal containing aluminum) Thermoplastic resin layer: Resin (polypropylene (PP) or polyphenylene sulfide (PPS)) Exterior body (support and cylinder): Made of metal (metal containing iron)

[0111] (Examples 1 to 6) In Examples 1 to 6, the shutoff pressure (safety valve shutoff pressure) Ps of the stripper disk, the material of the thermoplastic resin layer, and the resin fixing pressure Pt 23℃ , Resin fixing pressure Pt at abnormally high temperature (100℃) 100℃ The conditions were the same except that the thickness of the stripper disk was different. The safety valve shutoff pressure Ps was varied by changing the thickness of the stripper disk. The resin fixing pressure Pt was varied by changing the material or the fixing area of ​​the thermoplastic resin layer. The batteries of Examples 1 to 6 were batteries with a structure not including a beading portion as shown in FIG. 5.

[0112] (Comparative Examples 1 to 3) Comparative Example 1 corresponds to a battery having a conventional structure with a safety valve fixed by applying radial pressure via a gasket in an exterior body having a beading portion (corresponding to the structure of FIG. 12). Comparative Example 2 corresponds to a battery without a current path interruption mechanism. More specifically, it corresponds to a battery in which a flat plate terminal without a groove is bonded via a thermoplastic resin layer on the support portion of the exterior body, and the opening is blocked by the plate terminal. Comparative Example 3 corresponds to a battery in which the thermoplastic resin layer is positioned on the inner main surface 54b of the main surface of the support portion that faces the inside of the exterior body (corresponding to the structure of FIG. 13). That is, in the battery of Comparative Example 3, the safety valve is positioned inside the support portion in the battery axial direction.

[0113] The safety valve shutoff pressure, the resin fixing pressure in a normal state (23°C), and the resin fixing pressure in an abnormally high temperature state (100°C) were measured for each of the batteries of Examples 1 to 6 and Comparative Examples 1 to 3. In addition, an overcharge test based on the Electrical Appliance and Material Safety Act and a UL Projectile test (burner heating test) in accordance with the UL1642 standard were performed for each battery.

[0114] (Measurement of safety valve shutoff pressure) The safety valve shutoff pressure was measured by the following method. A constant current was applied to the safety cover and stripper disk of the safety valve via an external connection. Under this condition, a pressure of 0.33 kgf / cm was measured using a hydraulic booster. 2 The pressure was increased at a rate of 100 kPa / sec, and the pressure at which the current stopped flowing was taken as the cutoff pressure.

[0115] (Measurement of resin fixing pressure) The resin fixing pressure was measured by drilling a hole in the exterior body equipped with a safety valve and using a hydraulic booster to measure 0.33 kgf / cm 2 The internal pressure of the exterior body was increased at a rate of 100 / sec, and the pressure at the time when the hydraulic pressure was released was taken as the resin fixing pressure. The measurement was carried out under conditions where the temperature of the battery outer surface was 23°C and 100°C, and the resin fixing pressures at 23°C and 100°C were determined.

[0116] (Overcharge test) The fully discharged battery was charged at a constant current of 1.0 ItA to 250% of the nominal capacity using a charging power supply voltage of 18V while measuring the battery temperature, forcing it into an overcharged state. However, if the current path was cut off (i.e., current stopped flowing) due to the activation of the safety mechanism installed in the battery, the test was stopped at that point. It can be understood that the lower the maximum temperature reached in the test, the earlier the safety mechanism was activated and the more appropriately abnormal heat generation of the battery was suppressed. Therefore, a maximum temperature reached of 110°C or less was evaluated as best, a maximum temperature reached of 130°C or less was evaluated as good, and a maximum temperature reached of over 130°C was evaluated as poor.

[0117] (Heating test) A fully charged battery was fixed to the heating stand with wire. The battery was covered with an octagonal aluminum 17-mesh net and heated with a burner from underneath the heating stand until the battery caught fire or exploded. If the battery caught fire or exploded after the test, but none of its components were exposed outside the 17-mesh aluminum net, it was deemed to have passed the test. If the battery exploded and its components were exposed outside the net, it was deemed to have failed the test.

[0118] Based on the results of each test, an overall evaluation was made according to the following criteria. ◎: "Overcharge test result is 'best'" and "heat test result is 'pass'" 〇: "Overcharge test result is 'good'" and "heat test result is 'passed'" ×: "Overcharge test result is 'bad'" or "heat test result is 'failed'"

[0119] The results are shown in Table 1 below. [Table 1]

[0120] From the results in Table 1, in the batteries of Comparative Examples 1 and 3 in which the safety valve is held inside the exterior body via a gasket or a thermoplastic resin layer, the current path is interrupted in an overcharged state, but gas venting is insufficient in an abnormally high temperature state, and the batteries failed the UL Projectile test. On the other hand, in the batteries of Examples 1 to 6 in which the safety valve is disposed on the outside of the exterior body and the exterior body and the safety valve are fixed using a thermoplastic resin, it was possible to more safely cause the battery to fail in an overcharged state and an abnormally high temperature state. Therefore, it was found that the present invention provides a battery having a structure more suitable for a safety valve, which can perform suitable gas venting not only when the internal pressure increases abnormally in a non-abnormally high temperature state such as overcharge, but also in an abnormally high temperature state.

[0121] In addition, compared to the battery of Example 6 in which the resin fixing pressure in a non-abnormally high temperature state (23°C) was smaller than the safety valve shutoff pressure, the batteries of Examples 1 to 5 in which the resin fixing pressure in a non-abnormally high temperature state was larger than the safety valve shutoff pressure, obtained better results in the overcharge test. This is because in the batteries of Examples 1 to 5, the current path cutoff mechanism by the safety valve was activated in an overcharged state, making it possible to suitably stop charging, and the thermal cleavage mechanism in the thermoplastic resin layer was activated in an abnormally high temperature state. From this result, it was found that by making the resin fixing pressure in a non-abnormally high temperature state larger than the safety valve shutoff pressure and making the resin fixing pressure in an abnormally high temperature state smaller than the safety valve shutoff pressure, a more reliable battery can be obtained in which a more suitable safety mechanism can be selectively activated when the internal pressure of the exterior body rises in a non-abnormally high temperature state (for example, in an overcharged state) and in an abnormally high temperature state.

[0122] 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]

[0123] The battery according to the present invention (primary battery, secondary battery, etc.) 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 where 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 types of 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]

[0124] 10 Battery assembly 11 Positive electrode 12 Negative electrode 13 Separator 15 Conductive materials 50 Exterior body 52 Cylinder portion of exterior body 522 Body part of exterior body 524 Exterior body edge 54 Support part of exterior body 54a Outer surface of support 54b Inner surface of support 56 Exterior openings 56a Open end of exterior body 58 Beading section 100 Safety valve 110 Safety cover (first metal part) 110X central area 110Y Non-center area, outer area 112 Groove 120 Insulating materials 122 Opening area of ​​insulating material 130 Stripper disc (second metal member) 130X central area 130Y non-central area 132 Stripper disc groove 134 Stripper disc opening 140 Thermoplastic resin layer 150 Top cover 154 Top cover opening 1000 secondary battery

Claims

1. The battery includes an exterior housing that houses a battery assembly and an electrolyte, and a safety valve that is attached to the exterior housing; The battery assembly includes a positive electrode, a negative electrode, and a separator; The exterior body includes a cylindrical portion, a support portion that protrudes inward from the cylindrical portion at one end of the cylindrical portion, and an opening portion that is surrounded by the support portion, the safety valve is located at the one end of the barrel; The battery, wherein the safety valve and the support portion are fixed via a thermoplastic resin layer.

2. The support portion has an outer main surface located on the outer side of the exterior body, the relief valve is located on an outer major surface of the support; 2. The battery of claim 1, wherein the thermoplastic resin layer is interposed between the outer major surface and the safety valve.

3. The battery according to claim 1 , wherein in a normal state, the thermoplastic resin layer seals between the safety valve and the support portion.

4. the safety valve includes a first metal member located relatively to the outside of the battery and a second metal member located relatively to the inside of the battery, The battery according to claim 1 , wherein the second metal member has a groove portion that can be cleaved by internal pressure of the exterior body.

5. the first metal member has an outer circumferential portion extending radially outward beyond the second metal member, The battery according to claim 4 , wherein the support portion overlaps the outer peripheral portion via the thermoplastic resin layer.

6. The battery according to claim 4 , wherein the safety valve is provided on the exterior body via the thermoplastic resin layer that is disposed between the first metal member and the support portion.

7. The battery according to claim 4 , wherein in a normal state, a fixing pressure of the thermoplastic resin layer is greater than a cut-off pressure in the groove portion of the second metal member.

8. The battery according to claim 4 , wherein the fixing pressure of the thermoplastic resin layer is lower than the blocking pressure of the groove portion of the second metal member in an abnormally high temperature state.

9. The battery according to claim 1 , wherein the fixing pressure of the thermoplastic resin layer is lower than the internal pressure of the exterior body under an abnormally high temperature condition.

10. The battery according to claim 1 , wherein the melting point of the thermoplastic resin layer is 80° C. or higher and 340° C. or lower.

11. The battery of claim 1 , wherein the thermoplastic resin layer comprises a polyolefin-based resin.

12. The battery according to any one of claims 1 to 11, wherein the tubular portion of the exterior body has a structure that does not include a beading portion.

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