Battery and battery pack

Abstract

To provide a battery having a more suitable structure as a safety valve.SOLUTION: A battery includes a battery assembly, an exterior body having an opening at one end and housing the battery assembly, and a safety valve disposed in the opening, the safety valve includes an inner terminal positioned relatively inward and an outer terminal positioned relatively outward, the inner terminal includes a thin-walled portion which is ring-shaped in a plan view on the inner peripheral side of the opening end of the opening and is electrically connected to the battery assembly on the outer peripheral side of the thin-walled portion, and the outer terminal is fixed to the inner terminal in a state of being elastically deformed toward the inside of the exterior body on the inner peripheral side of the thin-walled portion, and the two are electrically connected to each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a battery and a battery pack that uses the battery. [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 Summary of the Invention [Problem to be solved by the invention]

[0004] Batteries and battery packs may be provided with a mechanism for ensuring their safety. For example, a battery and battery pack may be provided with a safety valve mechanism for suppressing the occurrence of malfunctions caused by gas when an abnormality occurs in the battery and gas is generated inside the battery (Patent Document 1). The inventors of the present application have earnestly examined whether there is still room for development of safety valve mechanisms for batteries and battery packs. As a result, they have found that there is still room for development of safety valves 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 and a battery pack having a more suitable structure as a safety valve. [Means for solving the problem]

[0006] The inventors of the present application attempted to solve the above problems by approaching them from a new direction, rather than by simply extending the conventional technology, and as a result, they have invented a battery and a battery pack that achieve the above-mentioned main object.

[0007] The battery according to the present invention comprises: a battery assembly; an exterior body having an opening at one end and housing the battery assembly; and a safety valve disposed in the opening; The safety valve includes an inner terminal located relatively inside and an outer terminal located relatively outside, the inner terminal has a thin-walled portion that is ring-shaped in a plan view on an inner circumferential side relative to an opening end of the opening, and is electrically connected to the battery assembly on an outer circumferential side relative to the thin-walled portion, The outer terminal is fixed to the inner terminal in a state in which the outer terminal is elastically deformed toward the inside of the exterior body on the inner circumferential side of the thin-walled portion, and the two are electrically connected to each other.

[0008] The battery pack according to the present invention further comprises: A battery and a battery holder for accommodating the battery, the battery holder includes an opening and a safety valve provided in the opening; the safety valve includes an inner terminal located relatively to the inside of the battery holder and an outer terminal located relatively to the outside of the battery holder, the inner terminal has a thin-walled portion extending radially inward from an opening end of the opening, and is electrically connected to the battery on an outer circumferential side of the thin-walled portion; The outer terminal is fixed to the inner terminal in a state in which the outer terminal is elastically deformed toward the inside of the battery holder, on a portion radially inward from the thin-walled portion. Effect of the Invention

[0009] In the battery and battery pack of the present invention, two terminals are incorporated in the safety valve. One terminal located on the outside of the battery and battery pack is fixed to the other terminal in a state where it is elastically deformed inward, and the battery and battery pack of the present invention have a safety valve structure that has not been seen before. This configuration makes it possible to appropriately cut off the current in the event of an abnormality. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic perspective view showing the appearance of a secondary battery according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the internal configuration of a secondary battery according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic perspective view showing components and related members of a safety valve of a secondary battery according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view of components of a safety valve of a secondary battery according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional perspective view showing a state before the safety valve of the secondary battery according to one embodiment of the present invention is activated. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a state before the safety valve of the secondary battery according to one embodiment of the present invention is activated. [Figure 7] FIG. 7 is a schematic cross-sectional view showing a state after the safety valve of the secondary battery according to one embodiment of the present invention has been activated. [Figure 8] FIG. 8 is a schematic cross-sectional view of a safety valve of a secondary battery according to one embodiment of the present invention. [Figure 9] FIG. 9 is an exploded perspective view showing a schematic diagram of an exterior body according to one embodiment of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view of a secondary battery according to one embodiment of the present invention. [Figure 11] FIG. 11 is a schematic cross-sectional view of a battery pack according to one embodiment of the present invention. [Figure 12]FIG. 12 is a schematic cross-sectional view showing a state before the safety valve of the battery pack according to one embodiment of the present invention is activated. [Figure 13] FIG. 13 is a schematic cross-sectional view showing a state after the safety valve of the battery pack according to one embodiment of the present invention has been activated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following describes the embodiments of the present invention in detail. Please note that the applicant provides the following description and examples so that those skilled in the art can fully understand the present invention, and that they do 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.

[0012] 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.

[0013] [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."

[0014] For convenience of explanation, the battery according to the present invention will be explained below mainly taking a secondary battery as an example.

[0015] The secondary battery according to the present invention has a battery assembly composed of electrode constituent layers including a positive electrode, a negative electrode, and a separator. The secondary battery according to the present invention may have a wound structure in which such electrode constituent layers are wound into a roll (hereinafter, also referred to as a "wound electrode body" or a "wound structure"). FIG. 1 shows an example of the external appearance of a secondary battery 1000, and FIG. 2 shows an example of its 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 and the negative electrode 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).

[0016] 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.

[0017] 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.

[0018] The electrode active materials contained in the positive electrode and the negative electrode, that is, the positive electrode active material and the negative electrode active material, respectively, are materials directly involved in the transfer of electrons in the secondary battery, and are the main materials of the positive and negative electrodes that are responsible for charging and discharging, i.e., the battery reaction. More specifically, ions are brought to the electrolyte due to the "positive electrode active material contained in the positive electrode material layer" and the "negative electrode active material contained in the negative electrode material layer", and these 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.

[0019] 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.

[0020] The lithium-containing composite oxide is a general term for oxides containing lithium and one or more other elements (elements other than lithium) as constituent elements, and may have any crystal structure such as a layered rock salt type and a spinel type, for example. The lithium-containing phosphate compound is a general term for phosphate compounds containing lithium and one or more other elements as constituent elements, and may have a crystal structure such as an olivine type, for example. The type of the other element is not particularly limited as long as it is any one or more of arbitrary elements. Among them, the other element is preferably any one or more of the elements belonging to Groups 2 to 15 in the long-period type periodic table. More specifically, the other element is, for example, nickel (Ni), cobalt (Co), manganese (Mn), iron (Fe), etc. This is because a high voltage can be easily obtained.

[0021] The lithium-containing composite oxide having a layered rock salt type crystal structure may be, for example, a compound represented by each of the following formulas (1) to (3). Li a Mn (1-b-c) Ni b M11 c O (2-d) F e ···(1) (M11 is at least one of cobalt (Co), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W). a to e satisfy 0.8 ≦ a ≦ 1.2, 0 < b < 0.5, 0 ≦ c ≦ 0.5, (b + c) < 1, -0.1 ≦ d ≦ 0.2, and 0 ≦ e ≦ 0.1. However, the composition of lithium varies depending on the charge-discharge state, and a is the value in the fully discharged state.) Li a Ni (1-b) M12 b O (2-c) F d ···(2) (M12 is at least one of cobalt (Co), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W). a to d satisfy 0.8≦a≦1.2, 0.005≦b≦0.5, -0.1≦c≦0.2, and 0≦d≦0.1. However, the composition of lithium varies depending on the charge / discharge state, and a is the value in a fully discharged state.) Li a Co (1-b) M13 b O (2-c) F d (3) (M13 is at least one of nickel (Ni), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W). a to d satisfy 0.8≦a≦1.2, 0≦b<0.5, -0.1≦c≦0.2, and 0≦d≦0.1. However, the composition of lithium varies depending on the charge / discharge state, and a is the value in a fully discharged state.) Specific examples of lithium-containing composite oxides having a layered rock salt type crystal structure include LiNiO2, LiCoO2, and LiCoO 0.98 Al 0.01 Mg 0.01 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.33 Co 0.33 Mn 0.33 O2, Li 1.2 Mn 0.52 Co 0.175 Ni 0.1 O2 and Li 1.15 (M 0.65 Ni0.22 Co 0.13 )O2, etc. When the lithium-containing composite oxide having a layered rock-salt crystal structure contains nickel, cobalt, manganese and aluminum as constituent elements, the atomic ratio of nickel is preferably 50 atomic % or more, because a high energy density is easily obtained.

[0022] 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.

[0023] 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.

[0024] 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.)

[0025] 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.

[0026] The positive electrode layer may contain a binder. In addition, the positive electrode layer may contain a positive electrode conductive agent to facilitate the transfer of electrons that promote the battery reaction. The binder of the positive electrode may contain, for example, one or more of synthetic rubber and polymer compounds. Examples of synthetic rubber include styrene butadiene rubber, fluorine-based rubber, and ethylene propylene diene. Examples of polymer compounds include polyvinylidene fluoride and polyimide. The positive electrode conductive agent may contain, for example, one or more of carbon materials. Examples of the carbon materials may include graphite, carbon black, acetylene black, and ketjen black. However, the positive electrode conductive agent may be a metal material, a conductive polymer, or the like, as long as it is a material that has conductivity.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] The "metal-based material" used as the negative electrode active material is a general term for a material containing one or more of metal elements and metalloid elements as constituent elements. When a carbon material is used as the negative electrode active material, a high energy density is easily obtained. The metal-based material may be a single substance, an alloy, a compound, or two or more of them, or may be a material containing at least one or more phases of them. However, the alloy may include a material containing one or more metal elements and one or more metalloid elements in addition to a material consisting of two or more metal elements. The alloy may also contain a nonmetallic element. The structure of this metal-based material may be, for example, a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or a coexistence of two or more of them. Such a metal element and metalloid element may be, for example, one or more of metal elements and metalloid elements that can form an alloy with lithium. Specifically, the metal element and the metalloid element may be, for example, magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), bismuth (Bi), cadmium (Cd), silver (Ag), zinc, hafnium (Hf), zirconium, yttrium (Y), palladium (Pd) and / or platinum (Pt). In a preferred embodiment, the metal element is silicon and tin. This is because they have excellent lithium absorption and release capabilities and are easy to obtain higher energy density. The material containing silicon as a constituent element may be silicon alone, a silicon alloy, a silicon compound, or two or more selected from them, or may be a material that contains one or more of these phases at least in a part. Similarly, a material containing tin as a constituent element may be a simple substance of tin, a tin alloy, a tin compound, or two or more of these, or may be a material that contains at least one or more of these phases in part. The term "simple substance" as used herein refers to a simple substance in the general sense, and may contain a trace amount of impurities.That is, the purity of the single substance is not necessarily limited to 100%. The silicon alloy 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. The silicon compound may contain, for example, any one or more of carbon and oxygen as constituent elements other than silicon. Note that the silicon compound may contain, for example, any one or more of the series of elements described for the silicon alloy as constituent elements other than silicon. Specific examples of the silicon alloy and specific examples of the silicon compound include SiB4, SiB6, MgSi, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu5Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, SiO. v (0 < v ≦ 2), and / or LiSiO, etc. can be cited. Note that for SiO v the v in it may be 0.2 < v < 1.4. The tin alloy 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. The tin compound may contain, for example, any one or more of carbon and oxygen as constituent elements other than tin. Note that the tin compound may contain, for example, any one or more of the series of elements described for the tin alloy as constituent elements other than tin. Specific examples of the tin alloy and specific examples of the tin compound include SnO w(0 < w ≤ 2), such as SnSiO3, LiSnO, and / or Mg2Sn, etc. can be cited. In particular, a material containing tin as a constituent element may be, for example, a material (tin-containing material) containing a second constituent element and a third constituent element together with tin which is the first constituent element. The second constituent element may be, for example, any one or more of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, zirconium, niobium, molybdenum, silver, indium, cesium (Ce), hafnium (Hf), tantalum, tungsten, bismuth, and silicon, etc. The third constituent element may be, for example, any one or more of boron, carbon, aluminum, and phosphorus, etc. This is because high battery capacity and excellent cycle characteristics, etc. are easily obtained. Among them, the tin-containing material may be a material (tin-cobalt-carbon-containing material) containing tin, cobalt, and carbon as constituent elements. This is because a high energy density is easily obtained. In the tin-cobalt-carbon-containing material, at least a part of the carbon which is a constituent element may be combined with a metal element or a metalloid element which is another constituent element. This is because aggregation of tin and crystallization of tin, etc. are easily suppressed. Such a tin-cobalt-carbon-containing material is not limited to a material (SnCoC) whose constituent elements are only tin, cobalt, and carbon. This tin-cobalt-carbon-containing material may contain, for example, in addition to tin, cobalt, and carbon, any one or more of silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, and bismuth, etc. as constituent elements. In addition to the tin-cobalt-carbon-containing material, it may also be a material (tin-cobalt-iron-carbon-containing material) containing tin, cobalt, iron, and carbon as constituent elements.

[0031] In addition, the negative electrode material may be, for example, any one or more of metal oxides and polymer compounds, etc. The metal oxide may be, for example, iron oxide, ruthenium oxide, and molybdenum oxide, etc. The polymer compound may be, for example, polyacetylene, polyaniline, and polypyrrole, etc.

[0032] The negative electrode material layer may contain a binder. Furthermore, the negative electrode material layer may contain a negative electrode conductive agent to facilitate the transfer of electrons that promote the battery reaction. The binder that may be contained in the negative electrode material layer is not particularly limited, but at least one selected from the group consisting of styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resins, and polyamideimide resins can be mentioned. The negative electrode conductive agent that may be contained in the negative electrode material layer is not particularly limited, but at least one selected from carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, carbon fibers such as graphite, carbon nanotubes, and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum, and silver, and polyphenylene derivatives can be mentioned. The negative electrode material layer may contain a component resulting from a thickener component (e.g., carboxymethyl cellulose) used during battery production.

[0033] 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.

[0034] 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.

[0035] The separator may be, for example, one or more of a porous film such as a synthetic resin and / or a ceramic, or may be a laminated film of two or more of the porous films. Examples of the synthetic resin used for the separator include polytetrafluoroethylene, polypropylene, and polyethylene. For example, the separator may include a porous film (substrate layer) and a polymer compound layer provided on one or both sides of the substrate layer. Since the adhesion of the separator to the positive electrode and the adhesion of the separator to the negative electrode can be improved, the distortion of the wound electrode body can be easily suppressed. The polymer compound layer may include, for example, one or more of a polymer compound such as polyvinylidene fluoride. The polymer compound layer has excellent physical strength and is easily electrochemically stable. The polymer compound layer may include, for example, one or more of insulating particles such as inorganic particles. The type of inorganic particles may be, for example, aluminum oxide and / or aluminum nitride. In the present invention, the separator should not be limited to a particular name, and may be a solid electrolyte, a gel electrolyte, and / or insulating inorganic particles having similar functions.

[0036] In the secondary battery of the present invention, a battery assembly consisting of electrode layers including a positive electrode, a negative electrode, and a separator may be enclosed in an exterior body together with an electrolyte. The electrolyte may be a so-called "non-aqueous" electrolyte.

[0037] Typically, the electrolyte includes a solvent and an electrolyte salt. The electrolyte may further include 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.

[0038] The solvent may include any one or more of non-aqueous solvents such as organic solvents. An electrolyte solution including a non-aqueous solvent may be a so-called non-aqueous electrolyte solution. The non-aqueous solvent may be, for example, a cyclic carbonate ester, a chain carbonate ester, a lactone, a chain carboxylate ester, and / or a nitrile (e.g., mononitrile). This is because it is easy to obtain better battery capacity, cycle characteristics, and / or storage characteristics. The cyclic carbonate ester may be, for example, ethylene carbonate, propylene carbonate, and / or butylene carbonate. The chain carbonate ester may be, for example, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and / or methyl propyl carbonate. The lactone may be, for example, γ-butyrolactone and / or γ-valerolactone. The chain carboxylate ester may be, for example, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, and / or ethyl trimethyl acetate. The nitrile may be, for example, acetonitrile, methoxyacetonitrile, and / or 3-methoxypropionitrile. In addition, the non-aqueous solvent may be, for example, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, N,N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N,N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate, and / or dimethyl sulfoxide. Among them, the non-aqueous solvent preferably contains one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. This is because it is easy to bring about a higher battery capacity, better cycle characteristics, and / or better storage characteristics. Furthermore, the non-aqueous solvent may be, for example, an unsaturated cyclic carbonate, a halogenated carbonate, a sulfonate, an acid anhydride, a dicyano compound (a dinitrile compound), a diisocyanate compound, a phosphate ester, and / or a chain compound having a carbon-carbon triple bond.This is because the chemical stability of the electrolyte solution is easily improved. The term "unsaturated cyclic carbonate" as used herein refers to a cyclic carbonate having one or more unsaturated bonds (carbon-carbon double bonds or carbon-carbon triple bonds). Examples of the unsaturated cyclic carbonate include vinylene carbonate, vinylethylene carbonate, and / or methyleneethylene carbonate. The term "halogenated carbonate" refers to a cyclic or chain-like carbonate containing one or more halogen elements as constituent elements. When the halogenated carbonate contains two or more halogens as constituent elements, the type of the two or more halogens may be only one type or may be two or more types. Examples of the cyclic halogenated carbonate include 4-fluoro-1,3-dioxolane-2-one and / or 4,5-difluoro-1,3-dioxolane-2-one. Examples of the chain-like halogenated carbonate include fluoromethyl methyl carbonate, bis(fluoromethyl) carbonate, and / or difluoromethyl methyl carbonate. The sulfonate ester may be, for example, a monosulfonate ester and / or a disulfonate ester. The monosulfonate ester may be, for example, a cyclic monosulfonate ester or a chain monosulfonate ester. The cyclic monosulfonate ester may be, for example, a sultone such as 1,3-propane sultone and / or 1,3-propene sultone. The chain monosulfonate ester is, for example, a compound in which a cyclic monosulfonate ester is cut in the middle. The disulfonate ester may be, for example, a cyclic disulfonate ester or a chain disulfonate ester. The acid anhydride may be, for example, a carboxylic acid anhydride, a disulfonic acid anhydride and / or a carboxylic acid sulfonic acid anhydride. The carboxylic acid anhydride may be, for example, succinic acid anhydride, glutaric acid anhydride and / or maleic acid anhydride. The disulfonic acid anhydride may be, for example, ethane disulfonic acid anhydride and / or propane disulfonic acid anhydride. The carboxylic acid sulfonic acid anhydride may be, for example, sulfobenzoic anhydride, sulfopropionic anhydride, and / or sulfobutyric anhydride, etc. The dinitrile compound may be, for example, NC-R1-CN (R1 is either an alkylene group or an arylene group).) is a compound represented by the formula: The dinitrile compound may be, for example, succinonitrile (NC-C2H4-CN), glutaronitrile (NC-C3H6-CN), adiponitrile (NC-C4H8-CN), phthalonitrile (NC-C6H4-CN), etc. The diisocyanate compound is, for example, a compound represented by the formula: OCN-R2-NCO (R2 is either an alkylene group or an arylene group). The diisocyanate compound is, for example, hexamethylene diisocyanate (OCN-C6H. 12 The phosphate ester may be, for example, trimethyl phosphate and triethyl phosphate. The chain compound having a carbon-carbon triple bond is a chain compound having one or more carbon-carbon triple bonds (-C≡C-). The chain compound having a carbon-carbon triple bond may be, for example, propargyl methyl carbonate (CH≡C-CH2-OC(=O)-O-CH3) and propargyl methylsulfonate (CH≡C-CH2-OS(=O)2-CH3).

[0039] 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.

[0040] The exterior body 50 used in the secondary battery corresponds to a member that encases a battery assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated as a battery exterior body. Such an exterior body 50 can also be called, for example, a "battery can." The exterior body 50 may have a hollow structure in which one end is closed and the other end is provided with an opening 52 (see Figs. 3 and 9). The opening 52 may be a through hole formed in one end of the exterior body 50. The exterior body may be a metal can containing any one or more of metal materials such as iron, aluminum, stainless steel, and alloys thereof, without being particularly limited thereto. The surface of the exterior body may be plated with any one or more of metal materials such as nickel. The opening 52 of the exterior body may be provided with a safety valve. Although this is merely an example, the opening 52 of the exterior body may be provided with a safety valve together with a thermosensitive resistor element or the like.

[0041] [Characteristics of the Battery of the Present Invention] The battery of the present invention has features related to a safety valve provided therein. In particular, the present invention has features related to a safety valve provided in the exterior body of the battery (particularly, in its opening). The battery of the present invention will be described below using a secondary battery as an example.

[0042] 1 and 2 are schematic diagrams showing the appearance and cross-sectional view of a battery of the present invention. As shown in the figures, a 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. A safety valve 100 may be provided at the cylindrical end of the battery 1000 (particularly the end on the opening 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.

[0043] The safety valve 100 provided in the battery of the present invention has at least a configuration in which a sealing member 110, a first terminal 120, an insulating member 130, and a second terminal 140 are combined in this order along a battery axis P. In this specification, the "battery axis" refers to an axis that passes through the center of the exterior body 50 and is perpendicular to the extension direction of the end face of the exterior body (particularly the end face on a virtual plane). In other words, the "battery axis" may mean an axis that passes through the center of the exterior body 50 in a plan view of the battery captured from the end side of the exterior body 50 where the safety valve 100 is arranged. 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.

[0044] The safety valve of the present invention includes a first terminal 120 located relatively inside and a second terminal 140 located relatively outside. In other words, the safety valve includes a first terminal 120 located relatively inside in the battery axial direction and a second terminal 140 located relatively outside in the battery axial direction. The first terminal 120 and the second terminal 140 can also be referred to as the "inner terminal 120" and the "outer terminal 140" based on their relative positional relationship. The first terminal 120 includes a thin-walled portion 126 that is ring-shaped in plan view on the inner periphery side of the opening end 53 of the exterior body. The thin-walled portion 126 may be formed in a substantially ring shape on the inner periphery side of the opening end 53 so as to resemble the shape of the opening end 53 in plan view. Hereinafter, in the first terminal 120, the inner periphery side of the thin-walled portion 126 is referred to as the center portion 122 of the first terminal, and the outer periphery side of the thin-walled portion 126 is referred to as the outer periphery portion 124 of the first terminal. In this specification, the "inner circumference side" can be interpreted as a side relatively closer to the battery axis P, and the "outer circumference side" can be interpreted as a side relatively farther from the battery axis P. At the outer circumference part 124 on the outer circumference side of the thin wall part 126, the first terminal 120 is electrically connected to the battery assembly 10 housed in the exterior body 50 via the conductive member 15. The second terminal 140 is fixed to the first terminal 120 on the inner circumference side of the thin wall part 126 in a state in which it is elastically deformed toward the inside of the exterior body 50. By this fixing, the battery assembly 10, the first terminal 120, and the second terminal 140 are electrically connected to each other. That is, the first terminal 120 and the second terminal 140 have the same polarity.

[0045] Since second terminal 140 is fixed to first terminal 120 in a state where it is elastically deformed toward the inside of exterior body 50, a restoring force that causes elastically deformed second terminal 140 to return to its original state (i.e., to be displaced toward the outside of exterior body 50) acts on the portion of first terminal 120 to which second terminal 140 is fixed. Due to this restoring force, a force that pulls second terminal 140 toward the outside of exterior body 50 acts on central portion 122 of the first terminal by second terminal 140 that is fixed to central portion 122 in an elastically deformed state.

[0046] Here, the effect of the present invention will be described in more detail in relation to the occurrence of an abnormality in the secondary battery. Figures 5 and 6 are schematic cross-sectional views of a battery in a normal state. The "normal state" refers to a state in which the internal pressure of the battery, i.e., the internal pressure of the exterior body 50, is within a normal range and the safety valve is not operating. As shown in the figures, the second terminal 140 is fixed to the center portion 122 of the first terminal in a state in which a part of it is elastically deformed toward the inside of the exterior body 50. In this state, the electrode assembly and the second terminal 140 are electrically connected to each other via the thin-walled portion 126 of the first terminal.

[0047] FIG. 7 is a schematic cross-sectional view showing a battery after the safety valve 100 is activated. When gas is generated inside the exterior body 50 due to an undesired side reaction such as overcharging of the battery or a decomposition reaction of the electrolyte, the gas accumulates inside the exterior body 50, and the internal pressure of the exterior body 50 rises. In addition, an undesired excessive increase in temperature inside the battery, such as a short circuit, can also cause an increase in the internal pressure of the exterior body 50. When the internal pressure of the exterior body 50 exceeds a certain predetermined pressure, the first terminal 120 is torn and separated as shown in FIG. 7. Specifically, when the internal pressure of the first terminal 120 rises, the first terminal 120 is torn and separated at the thin-walled portion 126 due to its thinness (small thickness). That is, when the internal pressure of the first terminal 120 exceeds a certain pressure, the first terminal 120 is torn and separated at the thin-walled portion 126 between the central portion 122 to which the second terminal 140 is fixed and the outer periphery portion 124 electrically connected to the battery assembly 10. Alternatively, when a split (crack) occurs in the thin-walled portion 126 of the first terminal and the current path from the battery assembly to the second terminal 140 becomes narrow, current concentration occurs in the thin-walled portion 126. This current concentration increases the temperature of the thin-walled portion 126, and the thin-walled portion 126 may melt. As a result, the first terminal may be divided into the central portion 122 and the outer peripheral portion 124 and / or melted. As a result, the central portion 122 of the first terminal may be physically separated from the outer peripheral portion 124 that is closer to the outer periphery than the central portion 122, and may be electrically cut off. In other words, due to an increase in internal pressure, the first terminal 120 may be divided into the central portion 122 electrically connected to the second terminal 140 and the outer peripheral portion 124 electrically connected to the battery assembly 10, and the electrical connection between the second terminal 140 and the battery assembly 10 may be cut off.

[0048] In this way, the first terminal 120 is cleaved at the thin portion 126 due to an increase in the internal pressure of the battery, and the electrical connection from the battery assembly 10 to the second terminal 140 is cut off. This makes it possible to stop side reactions involving the generation of undesired gas in the battery. At this time, according to the structure of the present invention, the cleavage and separation of the first terminal 120 in the event of an abnormality can be more reliably performed by utilizing the restoring force of the elastically deformed second terminal 140. Specifically, in the safety valve 100 of the present invention, a restoring force acts on the first terminal 120, which tends to displace the elastically deformed second terminal 140 toward the outside of the exterior body 50. When the internal pressure rises in the event of an abnormality, the restoring force has the effect of promoting the cleavage of the first terminal 120. Specifically, when the internal pressure of the battery rises abnormally, the second terminal 140 itself is displaced toward the outside of the battery along the battery axis direction. Since the second terminal 140 is fixed to the first terminal at the central portion 122, the central portion 122 of the first terminal can be pulled out as the terminal is displaced, and the central portion 122 can be displaced toward the outside of the battery together with the elastically deformed portion of the second terminal 140.

[0049] In the safety valve 200 thus activated, the first terminal is divided into a central portion 122 and an outer peripheral portion 124, and the central portion 122 and the outer peripheral portion 124 are not positioned on the same plane but are positioned offset from each other in the battery axial direction. Therefore, in the safety valve after activation, the central portion 122 and the outer peripheral portion 124 of the first terminal are more reliably separated from each other.

[0050] In the safety valve of the present invention, when the internal pressure of the battery rises, first terminal 120 is subjected to both a force pushing it from the inside of the battery toward the outside thereof due to the rise in internal pressure, and a force pulling it toward the outside of the battery due to the restoring force of second terminal 140. By applying these two forces to first terminal 120, current interruption can be more reliably achieved at first terminal 120.

[0051] Furthermore, according to the present invention, the first terminal 120 is torn and / or cut not only by a pushing force acting from the inside of the exterior body caused by an increase in the internal pressure of the exterior body 50, but also by a pulling force acting from the outside of the exterior body caused by the restoring force of the second terminal 140. Therefore, it is possible to tear and / or cut the first terminal even at a lower internal pressure. This makes it possible to operate a safety valve to cut off the current at an earlier stage when an abnormality occurs in the battery such as an increase in internal pressure. Therefore, according to the present invention, a battery with superior safety is provided.

[0052] Hereinafter, each component constituting the safety valve of the present invention will be described in more detail with reference to the drawings.

[0053] (1st terminal) The first terminal 120 is provided so as to close the opening 52 of the exterior body. For example, the first terminal 120 may be overlapped on an end surface 54 of the exterior body so as to cover the opening 52 of the exterior body. Note that an insulating sealing member 110 is disposed between the exterior body 50 and the first terminal 120. The exterior body 50 and the first terminal 120 may be electrically insulated by the sealing member 110.

[0054] The first terminal 120 may have a generally flat plate shape. For example, the first terminal 120 may have a shape that extends on the same plane. For example, the first terminal 120 may have a generally constant thickness except for the thin portion 126.

[0055] The planar shape of the first terminal 120, particularly the outer contour shape in plan view (hereinafter also referred to as "outer contour shape in plan view") is not particularly limited, and may be, for example, a circle, a polygon, or other shapes. The circle is, 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 is, for example, a triangle, a square, a pentagon, and a hexagon. Other shapes are, for example, shapes 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. The definition of "circle" and the like is the same hereinafter. In the illustrated exemplary embodiment, the outer contour shape in plan view of the first terminal 120 is a circle. In addition, in the present invention, "plan view" is based on a sketch when the object is viewed along the battery axis direction.

[0056] The first terminal 120 may be a metal member. For example, the first terminal 120 may include a metal material including at least one selected from the group consisting of aluminum (e.g., aluminum alloys such as A1050, A3203, and A5052), nickel, titanium, platinum, copper, gold, stainless steel, and the like. In other words, the first terminal 120 may be a member made of such a conductive material. The material of the first terminal 120 may be the same as the material of the second terminal 140, or may be a different material.

[0057] The first terminal 120 has a first surface 120a facing the inside of the exterior body 50 and a second surface 120b located on the opposite side of the first surface 120a. The first terminal 120 has a thin-walled portion 126 on the first surface 120a and / or the second surface 120b. The "thin-walled portion" refers to a portion where the thickness of the first terminal 120 is locally reduced in a cross-sectional view. In other words, the "thin-walled portion" has a thickness smaller than the thickness of the other portions of the first terminal 120. Therefore, the thin-walled portion can also be referred to as a "relatively reduced thickness portion" or the like. More specifically, the "thin-walled portion" is a portion having a thickness of 5% to 70% of the thickness of the portion of the first terminal 120 at the battery axis P. For example, the thin-walled portion 126 may be formed by a groove portion formed on the first surface 120a and / or the second surface 120b of the first terminal. With this structure, if the internal pressure of exterior body 50 increases due to an abnormality, first terminal 120 can be cleaved at thin portion 126.

[0058] The cross-sectional shape of the thin-walled portion 126 is not particularly limited. For example, the cross-sectional shape of the first terminal 120 at the thin-walled portion 126 (particularly, the cross-sectional shape of the hollow portion that provides the thin-walled portion 126) may be a curved shape such as a substantially V-shape, a rectangular shape, a polygonal shape, or a substantially U-shape. Alternatively, it may be a shape that combines two or more of any shapes such as a rectangular shape, a polygonal shape, and a curved shape. In this specification, the "cross-sectional shape" refers to the shape of a cross section when the first terminal 120 is cut along the thickness direction.

[0059] The thin-walled portion 126 may extend along the opening end 53 of the exterior body on the inner periphery side of the opening end 53. The thin-walled portion 126 may have a ring-shaped shape in a plan view. That is, the thin-walled portion 126 may extend in a ring shape along the opening end 53 so as to surround the battery axis P. In this specification, "ring-shaped" means a so-called ring shape. Therefore, the shape formed by the thin-walled portion 126 does not necessarily have to be circular, and may be any shape such as a polygonal shape. In addition, the "ring-shaped" does not necessarily have to be a shape that is completely closed all around, and may be partially interrupted. For example, the thin-walled portion 126 may be formed intermittently along the opening end 53 of the exterior body, or may extend continuously along the opening end 53 of the opening.

[0060] The first terminal 120 may be electrically connected to the conductive member 15 extending from the battery assembly 10 at the outer periphery 124. More specifically, the first terminal 120 is in physical contact with the conductive member 15 extending from the battery assembly at the outer periphery 124 of the first surface 120a, and is electrically connected to the battery assembly. The first terminal 120 is also electrically connected to the second terminal 140 at the center 122 of the second surface 120b. That is, the battery assembly 10 and the second terminal 140 are electrically connected to each other via the first terminal 120. The thin portion 126 is positioned between the connection portion between the battery assembly 10 and the first terminal 120 and the connection portion (fixed portion 150) between the first terminal 120 and the second terminal 140. Therefore, it can be understood that the battery assembly 10 and the second terminal 140 are electrically connected via the thin portion 126 of the first terminal. With this configuration, when first terminal 120 is cleaved at thin portion 126, the electrical connection between battery assembly 10 and second terminal 140 is cut off.

[0061] (Sealing member) An insulating sealing member 110 is disposed between the exterior body 50 and the first terminal 120. The sealing member 110 seals the gap between the exterior body 50 and the first terminal 120, and electrically insulates the exterior body 50 from the first terminal 120. The sealing member 110 may have a ring-shaped or annular shape in plan view having a through hole similar to the opening shape of the opening of the exterior body. That is, the sealing member 110 is an annular insulating member 130 disposed at the end of the exterior body 50 having an opening so as to be interposed between an end surface 54 of the exterior body and the first terminal 120.

[0062] (2nd terminal) The second terminal 140 may be disposed so as to overlap the first terminal 120 so as to cover the opening 52 of the exterior body. The planar shape of the second terminal 140, particularly the outer contour shape in plan view, is not particularly limited, and may be, for example, a circle, a polygon, or other shape. The second terminal 140 may be a metal member that is elastically deformable by external pressure and has excellent electrical conductivity. For example, the second terminal 140 may include a metal material including at least one selected from the group consisting of aluminum (for example, aluminum alloys such as A1050, A3203, and A5052), nickel, titanium, platinum, copper, gold, and stainless steel. In other words, the second terminal 140 may be a member made of such a conductive material.

[0063] The thickness of second terminal 140 is not particularly limited as long as it is elastically deformable in the battery axial direction, but may be 0.20 mm or less, 0.18 mm or less, or 0.15 mm or less, if emphasis is placed on the ability of the restoring force from an elastically deformed state to act favorably on first terminal 120. Furthermore, if emphasis is placed on the strength required to avoid breakage of second terminal 140 during elastic deformation and during restoration deformation upon operation of the safety valve, the thickness of second terminal 140 may be 0.03 mm or more, 0.05 mm or more, or 0.07 mm or more.

[0064] The second terminal 140 has a first surface 140a facing the first terminal 120 and a second surface 140b located on the opposite side to the first surface 140a. The second terminal 140 is fixed to the first surface 120a of the first terminal in a state where it is elastically deformed toward the inside of the exterior body 50, and is thereby electrically connected to the first terminal 120. More specifically, the second terminal 140 has an outer peripheral portion 144 and a central portion 142 surrounded by the outer peripheral portion 144, and the central portion 142 of the second terminal is held in an elastically deformed state by being fixed to a portion (i.e., the central portion 122 of the first terminal) on the inner peripheral side of the thin portion 126 of the first terminal in a state where it is elastically deformed so as to be recessed toward the inside of the exterior body 50. In such a structure, the central portion 142 of the second terminal is located relatively closer to the inside of the exterior body 50 than the outer peripheral portion 144 of the second terminal. In other words, the outer periphery 144 of the second terminal is located relatively further outward in the battery axis direction than the center portion 142 of the second terminal.

[0065] According to the above-mentioned structure, the second terminal 140 is fixed in a state in which the central portion 142 is elastically deformed toward the first terminal 120. A restoring force acts on the central portion 142 of the second terminal to return it to its original state from the elastically deformed state, while the fixed portion 150 between the first terminal 120 and the second terminal 140 maintains the elastically deformed state of the second terminal 140. Therefore, a force acts on the central portion 122 of the first terminal to which the second terminal 140 is fixed, which forces the central portion 142 of the second terminal to be displaced in the opposite direction, that is, toward the outside of the exterior body 50, from the state in which the central portion 142 of the second terminal is elastically deformed toward the inside of the exterior body 50. In short, in a state in which the second terminal 140 is fixed, a force acts on the central portion 122 of the first terminal to pull it toward the outside of the exterior body 50 by the second terminal 140. This action helps the first terminal 120 to break open when the internal pressure of the battery increases. That is, according to the present invention, a battery can be provided that is equipped with a safety valve that can more appropriately cut off current in the event of an abnormality.

[0066] The first terminal 120 and the second terminal 140 are preferably fixed to such an extent that the fixation is not released with the operation of the safety valve even when the internal pressure of the battery increases. For example, the fixing part 150 is preferably fixed firmly to such an extent that the fixation between the first terminal 120 and the second terminal 140 is not released with the displacement of the second terminal 140. Furthermore, the fixing part 150 preferably contributes to electrical conduction between the first terminal 120 and the second terminal 140. In other words, the first terminal 120 and the second terminal 140 may be electrically conducted via the fixing part 150. The first terminal 120 and the second terminal 140 may be fixed by, for example, laser welding.

[0067] The fixing portion 150 between the first terminal 120 and the second terminal 140 is positioned on the inner circumferential side of the thin-walled portion 126. The fixing portion 150 may be positioned closer to the thin-walled portion 126 than the battery axis P. Preferably, the fixing portion 150 is positioned on the inner circumferential side of the thin-walled portion 126 so as to be along the thin-walled portion 126. That is, the fixing portion 150 is preferably provided at a position closer to the thin-walled portion 126. This makes it easier for the restoring force of the second terminal 140 to act on the thin-walled portion 126 of the first terminal. Therefore, when the internal pressure of the battery increases and the first terminal 120 is torn at the thin-walled portion 126, the torn can be more suitably promoted by the restoring force of the second terminal 140.

[0068] For example, the first terminal 120 and the second terminal 140 may be fixed at a plurality of locations on the inner circumferential side of the thin-walled portion 126. When the fixing portions 150 are provided at a plurality of locations, it is preferable that the fixing portions 150 are positioned so as to be point-symmetric with respect to the battery axis P. For example, the safety valve may be provided with fixing portions 150 at four or more locations, six or more locations, or eight or more locations so as to be point-symmetric with respect to the battery axis P. With such a structure, the restoring force of the second terminal 140 acts more evenly on the first terminal 120, so that when the internal pressure rises, the first terminal 120 can be more reliably split open to cut off the current.

[0069] The fixing portion 150 between the first terminal 120 and the second terminal 140 may be positioned intermittently along the thin-walled portion 126 on the inner circumferential side of the thin-walled portion 126. Alternatively, the fixing portion 150 may extend continuously along the thin-walled portion 126 on the inner circumferential side of the thin-walled portion 126. That is, the fixing portion 150 may be provided in a substantially annular shape so as to correspond to the planar shape of the thin-walled portion 126. Here, the term "substantially annular" is not necessarily limited to a continuous annular shape whose entire circumference is completely closed, but also includes a discontinuous annular shape having a notch in a part. This allows the second terminal 140 to be more reliably fixed to the first terminal 120, so that the center portion 142 of the second terminal can be suitably held in an elastically deformed state in a normal state in which the internal pressure of the battery is not increased.

[0070] Further, on the inner circumferential side of the thin portion 126, a non-fixed region where the first terminal 120 and the second terminal 140 are not fixed may be provided. In other words, the first terminal 120 and the second terminal 140 may be fixed in a part of the region on the inner circumferential side of the thin portion 126. That is, the central portion 122 on the inner circumferential side of the thin portion 126 may include a fixed portion 150 where the first terminal 120 and the second terminal 140 are fixed, and a non-fixed region where they are not fixed. If the first terminal 120 and the second terminal 140 are fixed in the entire region of the central portion 122, the elastically deformed second terminal 140 is firmly fixed, and the restoring force can be suppressed. Thereby, the action of promoting cleavage when the internal pressure of the battery increases may be suppressed. On the other hand, by providing a non-fixed region, it is possible to avoid the second terminal 140 being fixed excessively firmly. Therefore, under normal conditions, the second terminal 140 is held in an elastically deformed state, and when the internal battery pressure increases, the restoring force of the second terminal 140 can be advantageously utilized to break open the first terminal 120.

[0071] Preferably, the non-fixed region may be positioned at the battery axis P. That is, the non-fixed region may be positioned around the battery axis P, and the fixed portion 150 between the first terminal 120 and the second terminal 140 may be positioned around the non-fixed region. In other words, the fixed portion 150 between the first terminal 120 and the second terminal 140 may be provided on the outer periphery side of the non-fixed region positioned at the battery axis P. According to this configuration, the fixed portion 150 is positioned closer to the thin portion 126 than the non-fixed region. The restoring force of the second terminal 140 toward the outside of the exterior body 50 acts more strongly on the fixed portion 150 than on the non-fixed region. By positioning the fixed portion 150 closer to the thin portion 126, the restoring force of the second terminal 140 can be more efficiently applied to the thin portion 126. Therefore, when the internal pressure of the battery increases, the first terminal 120 can be more suitably opened.

[0072] As described above, the safety valve of the present invention cleaves and separates the first terminal 120 by the increased internal pressure and the restoring force of the second terminal 140 when the internal pressure of the battery rises during an abnormality such as overcharging. In order to increase the internal pressure by the gas generated inside and quickly activate the safety valve, the battery equipped with the safety valve of the present invention is preferably sealed. Since the exterior body 50 is open at an opening formed at one end, the battery is preferably sealed by the safety valve. In other words, the safety valve may seal the opening to hermetically seal the inside of the battery.

[0073] (Insulating material) An insulating member 130 may be disposed between the first terminal 120 and the second terminal 140 on the outer circumferential side of the thin-walled portion 126. That is, on the outer circumferential side of the thin-walled portion 126, the first terminal 120 and the second terminal 140 may be disposed so as to sandwich the insulating member 130. The insulating member 130 may have a circular or ring-shaped shape in plan view. The insulating member 130 may have a through hole 132 located at the battery axis P. In plan view, the through hole 132 may have a hole shape corresponding to the shape of the central portion 122 of the first terminal in plan view. The insulating member 130 may be positioned on the outer circumferential side of the thin-walled portion 126, and the second terminal 140 may be elastically deformed toward the first terminal 120 via the through hole 132 of the insulating member 130 on the inner circumferential side of the thin-walled portion 126 so as to straddle the insulating member 130, and may be electrically connected to the first terminal 120. That is, the first terminal 120 and the second terminal 140 are connected on the inner circumferential side of the thin-walled portion 126, while being separated by the insulating member 130 on the outer circumferential side of the thin-walled portion 126. With this configuration, when the safety valve is activated and the first terminal 120 is disconnected, the first terminal 120 and the second terminal 140 are electrically insulated by the insulating member 130 on the outer circumferential side of the thin-walled portion 126, so that electrical continuity between the battery assembly 10 and the second terminal 140 can be suitably interrupted.

[0074] In this specification, "insulating" may have the insulating properties and therefore the electrical resistivity of a typical insulator. By way of example only, an "insulating" member may have an electrical 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 an electrical resistivity of Ω·m or more (at room temperature of 20°C).

[0075] The insulating member 130 may be an insulating resin member. That is, the insulating member 130 preferably contains a resin component. This provides suitable insulation (particularly electrical insulation) between the outer periphery 124 of the first terminal and the outer periphery 144 of the second terminal. If more importance is placed on exhibiting suitable resistance to undesirable heat in the event of a battery abnormality, the insulating member 130 preferably contains a resin with excellent heat resistance. For example, the insulating member 130 may be made of a thermosetting resin, a thermoplastic resin, and / or a UV-curable resin. Specific resin components of insulating member 130 are not particularly limited, but may include at least one selected from the group consisting of polyethylene resin, polypropylene resin, polystyrene resin, ABS resin (acrylonitrile (A)-butadiene (B)-styrene (S) resin), vinyl chloride resin, polymethyl methacrylate resin, polyethylene terephthalate resin, polyamide resin, polycarbonate resin, polyacetal resin, polybutylene terephthalate resin, modified polyphenylene ether resin, polyphenylene sulfide resin, liquid crystal polymer, polyarylate resin, polysulfone resin, polyethersulfone resin, and polyetheretherketone resin.

[0076] The insulating member 130 may be bonded to each of the outer peripheries 124, 144 of the first terminal and the second terminal. Specifically, the insulating member 130 may be bonded to each of the outer periphery 124 of the second surface 120b of the first terminal 120 and the outer periphery 144 of the first surface 140a of the second terminal. The outer peripheries of the first terminal 120 and the second terminal 140 can be fixed to each other by this adhesion. In particular, since the outer periphery 144 of the second terminal is fixed by adhesion to the insulating member 130, when the internal pressure of the battery increases, a restoring force can act more efficiently on the central portion 142 of the elastically deformed second terminal. Therefore, when the internal pressure of the battery increases, the first terminal 120 can be more reliably opened and divided.

[0077] Furthermore, the adhesion between the insulating member 130 and each of the first terminal 120 and the second terminal 140 may contribute to sealing between the insulating member 130 and the first terminal 120 and between the insulating member 130 and the second terminal 140. For example, the adhesion may be achieved by an adhesive layer 160 provided between the insulating member 130 and the first terminal 120 and between the insulating member 130 and the second terminal 140, and the adhesive layer 160 may seal between the insulating member 130 and each of the first terminal 120 and the second terminal 140. With this structure, in the event of an abnormality such as overcharging, gas generated inside is prevented from immediately leaking out to the outside, and the internal pressure of the battery is increased, thereby allowing the safety valve to be suitably operated.

[0078] The adhesive layer 160 positioned on the insulating member 130 may be a thermoplastic resin. That is, the insulating member 130 and the outer periphery 124 of the first terminal, the insulating member 130 and the outer periphery 144 of the second terminal, and / or the insulating member 130 and the exterior body 50 may be fixed by a thermoplastic resin. As described above, when an abnormality of an internal pressure increase occurs inside the battery due to overcharging or the like caused by a short circuit, it may occur in combination with an abnormality such as an increase in the battery temperature. That is, in addition to an increase in pressure inside the battery can due to a side reaction such as a decomposition reaction of the electrolyte or other factors, an undesirable increase in temperature inside the battery may occur. In a structure in which a thermoplastic resin is arranged between the insulating member 130 and the first terminal 120, between the insulating member 130 and the second terminal 140, and / or between the insulating member 130 and the exterior body 50, when the temperature of the battery increases, the thermoplastic resin may flow. At this time, the internal pressure of the battery increases due to the gas generated inside the battery, and the gas filling the inside of the battery may leak out, pushing aside the thermoplastic resin that has become flowable due to the high temperature. In other words, when the internal pressure of the battery increases and the battery becomes hotter, the thermoplastic resin disposed between the insulating member 130 and the terminals can serve as a gas release mechanism (or vent mechanism) to release the internal pressure by releasing the gas accumulated inside, thereby preventing the battery from exploding. This can provide a safety valve that has a gas release mechanism in addition to a current interruption mechanism.

[0079] Examples of the thermoplastic resin include at least one selected from the group consisting of polyethylene resin, polypropylene resin, polystyrene resin, ABS resin (acrylonitrile (A)-butadiene (B)-styrene (S) resin), vinyl chloride resin, polymethyl methacrylate resin, polyethylene terephthalate resin, polyamide resin, polycarbonate resin, polyacetal resin, polybutylene terephthalate resin, modified polyphenylene ether resin, polyphenylene sulfide resin, liquid crystal polymer, polyarylate resin, polysulfone resin, polyethersulfone resin, and polyetheretherketone resin.

[0080] The insulating member 130 is preferably made of a material having better heat resistance than the thermoplastic resin used as the adhesive layer. More specifically, the insulating member 130 is preferably made of a material that is less likely to soften under high temperature conditions than the adhesive layer 160. This makes it possible to suitably maintain electrical insulation between the outer periphery 124 of the first terminal and the outer periphery 144 of the second terminal even at high temperatures.

[0081] Insulating member 130 is located on the outer periphery side of thin-walled portion 126 of the first terminal, and may extend from thin-walled portion 126 to edge portion 57 that forms the boundary between end surface 52 and side surface 58 of the exterior body. In one embodiment, insulating member 130 may be provided so as to extend from thin-walled portion 126 to side surface 58 of the exterior body. In such a structure, insulating member 130 is provided so as to cover edge portion 57 that extends between end surface 54 and side surface 58 of the exterior body.

[0082] In a mode in which the insulating member 130 is provided so as to extend to the side surface 58 of the exterior body, the insulating member 130 may be adhered to the side surface 58 of the exterior body (see FIG. 8). That is, the insulating member 130 and the side surface 58 of the exterior body may be adhered to each other. With this structure, the insulating member 130 can be suitably fixed to the exterior body 50 even when the internal pressure of the battery increases. Therefore, the insulating member 130 can suitably prevent the risk of the safety valve being blown off due to an increase in internal pressure, and can suitably fix the safety valve to the exterior body 50.

[0083] The insulating member 130 and the side surface 58 of the exterior body may be bonded together by the above-mentioned thermoplastic resin. In other words, a thermoplastic resin may be disposed between the insulating member 130 and the side surface 58 of the exterior body, and the insulating member 130 may be fixed to the exterior body 50 by the thermoplastic resin. By disposing the thermoplastic resin, when the temperature of the battery becomes high due to abnormal heat generation or the like, gas generated inside the battery can be suitably released from the portion of the thermoplastic resin whose fluidity has increased due to the high temperature.

[0084] In one embodiment, the sealing member 110 disposed between the exterior body 50 and the first terminal 120 may be made of, for example, a thermosetting resin, a thermoplastic resin, and / or a UV-curable resin. In particular, when emphasis is placed on gas escape properties when the battery becomes hot, the sealing member 110 may be a thermoplastic resin. By using a thermoplastic resin as the sealing member 110, the sealing member 110 may soften when the battery becomes undesirably hot. Thereafter, the gas inside the battery is released to the outside as if pushing aside the softened sealing member 110, and the internal gas pressure can be released.

[0085] As described above, the battery of the present invention may include a safety valve that includes both a current interruption mechanism that splits and breaks the first terminal 120, and a gas venting mechanism that uses adhesion using a thermoplastic resin. Of the two mechanisms, the current interruption mechanism utilizes the force that pushes the first terminal 120 toward the outside of the exterior part as the internal pressure of the battery increases, in addition to the restoring force of the second terminal 140. Therefore, if the gas venting mechanism operates before the current interruption mechanism operates, the internal pressure of the battery may not increase to a predetermined pressure required for splitting and breaking the first terminal 120, and the current interruption mechanism may not operate normally. Therefore, it is preferable that the inside of the battery is sealed until the current interruption mechanism operates (i.e., at least the thin-walled part 126 of the first terminal splits). In particular, when an abnormality occurs inside the battery at room temperature and the internal pressure of the battery rises, it is preferable that the safety valve operates in the following order: (i) first terminal 120 breaks open at thin portion 126, (ii) elastically deformed second terminal 140 is displaced toward the exterior body, and (iii) gas is released from the adhesive portion. Therefore, it is preferable that the internal pressure of exterior body 50 required for (i) breakage, (ii) displacement, and (iii) gas release is designed to be in the order of (i)<(ii)<(iii).

[0086] According to the present invention, the safety valve can be arranged on the end surface 54 of the exterior body having an opening so as to cover the opening. That is, in the battery of the present invention, the safety valve can be arranged on the opening so as to cover the opening. In such a structure, the safety valve is positioned on the outer side of the exterior body 50. This makes it possible to omit the space for arranging the safety valve inside the exterior body 50. Therefore, it becomes possible to arrange a larger battery assembly inside the exterior body 50, and it becomes possible to improve the energy density per volume of the battery. That is, according to the present invention, it becomes possible to provide a safety valve without reducing the capacity of the battery, and therefore a battery that is preferable in terms of battery capacity and safety can be provided.

[0087] In a conventional safety valve structure, a safety valve is disposed in an exterior body having a beading portion 56 (see FIG. 9) formed around the outer periphery of the exterior body side surface 58. The "beading portion" refers to a portion of the exterior body side surface 58 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, and can also be called a "constricted portion" or a "narrowed portion". Conventionally, in a battery having an exterior body having a beading portion, a support member such as a gasket is disposed in the beading portion, and the safety valve is held inside the exterior body via the gasket portion (Patent Document 1). In other words, the conventional safety valve is disposed inside the exterior body having the beading portion.

[0088] In contrast, according to the present invention, since the safety valve can be disposed on the outer side of the exterior body, the safety valve can be disposed without the need for a support member such as a gasket. Therefore, a battery having a simpler structure and a safety valve can be provided. Furthermore, according to the present invention, the safety valve can be disposed without relying on the beading portion 56. Therefore, the safety valve can be disposed not only in the exterior body having the beading portion 56, but also in the exterior body having no beading portion (see FIG. 5). That is, according to the present invention, the safety valve can be disposed suitably regardless of the presence or absence of the beading portion. In the exterior body 50, 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 of the exterior body in which the battery assembly can be disposed, compared with the exterior body 50 having the beading portion 56 (see FIGS. 9 and 10). That is, according to the present invention, the safety valve can be disposed even in the exterior body having no beading portion, which enables a high energy density, and therefore a battery having a high energy density and excellent safety can be obtained.

[0089] In the exterior body 50, the end surface 54 of the exterior body to which the safety valve 100 is attached may be a cover member 54A attached to one end of the exterior body 50 by welding, adhesive, or the like. Specifically, the exterior body 50 without a beading portion may include a cylindrical body 55 including an open end that is opened at one end, and the end surface 54 of the exterior body may be formed by attaching a cover member 54A having an opening to the open end. According to such a structure, the cover member 54A can also be understood as a member that supports the safety valve at the end of the exterior body, and may also be called a support member, etc. The cover member 54A may be a conductive member or an insulating resin member.

[0090] (Secondary battery manufacturing) A method for producing a secondary battery will now be described by way of example. The secondary battery of the present invention can be produced, for example, by the following procedure.

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

[0092] When assembling a secondary battery, 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 together with the pair of insulating plates is stored inside the exterior body. In this case, one end of the positive electrode lead is connected to the outer periphery 124 of the first terminal of 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. The safety valve is formed by combining a sealing member, a first terminal, an insulating member, and a second terminal in this order. At this time, adhesive layers are disposed between the first terminal and the insulating member, and between the second terminal and the insulating member, respectively, to bond the members together. After the members are assembled, the center portion 142 of the second terminal is pressed toward the center portion 122 of the first terminal, causing elastic deformation. Next, the second terminal is fixed to the first terminal in an elastically deformed state by using a welding method or the like. The safety valve assembled in this manner is disposed in the opening of the exterior body, and the exterior body is sealed. This completes a secondary battery equipped with a safety valve.

[0093] [Basic battery pack configuration] Next, an example of the configuration of a battery pack will be described with reference to the drawings. Fig. 11 is a schematic cross-sectional view of a battery pack according to one embodiment of the present invention. Fig. 12 is an enlarged cross-sectional view showing a schematic structure of a safety valve in a battery pack of the present invention before activation. Fig. 13 is an enlarged cross-sectional view showing a schematic structure of a safety valve in a battery pack of the present invention after activation.

[0094] The battery pack 2000 includes at least a battery 1000 and a battery holder 500 that houses the battery 1000. The battery 1000 housed in the battery holder 500 may be electrically connected to a terminal provided on a safety valve attached to the battery holder 500 via a conductive member 25 such as a conductive lead extending from a terminal (not shown) of the battery 1000.

[0095] The battery holder 500 may be an insulating resin member. By way of example only, the battery holder 500 may be made of one or more of resin materials such as polypropylene (PP) and polycarbonate.

[0096] The battery pack 2000 may, for example, house a single battery 1000, or may include two or more batteries 1000. One battery holder 500 may house one battery 1000. When the battery pack 500 includes two or more batteries 1000, the two or more battery holders 500 may be connected to each other. Alternatively, one battery holder 500 may be configured to house multiple batteries 1000. The multiple batteries 1000 housed in the battery holder 500 may be connected in series and / or parallel by a connection plate (not shown) installed outside the battery holder 500.

[0097] [Characteristics of the battery pack of the present invention] The structure of the battery safety valve as described above can also be applied as a safety valve provided in a battery holder of a battery pack. For example, the battery holder 500 may be provided with a terminal plate that functions as a safety valve as a terminal plate electrically connected to one terminal of the battery 1000 housed inside the battery holder 500. The battery holder 500 has an opening 550 that is partially open. The safety valve 200 provided with the terminal plate may be provided so as to cover the opening 550. The safety valve 200 may be provided on the outer side of the battery holder 500. The safety valve 200 has a first terminal plate 220 that is relatively located closer to the battery holder 500 and a second terminal plate 240 that is relatively located closer to the outside of the battery pack 550. The first terminal plate 220 has a thin-walled portion 226 that is relatively located on the inner periphery side of the opening end 555 of the opening 550 of the battery holder. The first terminal plate 220 is electrically connected to the battery 1000 in the battery holder 500 on the outer periphery side of the thin-walled portion 226, and is electrically connected to the second terminal plate 240 on the inner periphery side of the thin-walled portion 226. The second terminal plate 240 is fixed to the first terminal plate 220 in a state in which it is elastically deformed toward the inside of the battery holder 500 on the inner periphery side of the thin-walled portion 226, thereby being electrically connected to the first terminal plate 220. In other words, the battery 1000 accommodated in the battery holder 500 is electrically connected to the second terminal plate 240 via the thin-walled portion 226 of the first terminal plate.

[0098] According to the above-described structure, if an abnormality occurs in the battery 1000 housed in the battery holder 500 and the internal pressure of the battery holder 500 rises due to the generation of undesired gas, the first terminal plate 220 can be torn and separated at the thin-walled portion 226 due to the combined effects of the internal pressure and the restoring force of the elastically deformed second terminal plate 240. This can cut off the electrical connection between the battery 1000 in the battery holder 500 and the second terminal 240 located outside the battery holder 500.

[0099] The battery holder 500 may have an end surface 510 around the opening 550. The end surface 510 may be interpreted as a protruding surface extending from the side surface 520 of the battery holder toward the opening 550, and may be referred to as an "end surface protruding portion." On the outer circumferential side of the thin-walled portion 226, the end surface 510 of the battery holder may be interposed between the first terminal plate 220 and the second terminal plate 240. In other words, on the outer circumferential side of the thin-walled portion 226, the first terminal plate 220 and the second terminal plate 249 may be electrically insulated by the battery holder 500. This ensures that the current between the first terminal plate 220 and the second terminal plate 240 can be interrupted even after the first terminal plate 220 is separated.

[0100] Furthermore, end surface 510 of the battery holder disposed between first terminal plate 220 and second terminal plate 240 may be bonded to first terminal plate 220 and second terminal plate 240 by adhesive layer 260 such as resin. This allows first terminal plate 220 and second terminal plate 240 to be suitably held to battery holder 500. Therefore, when the internal pressure of battery holder 500 increases, current can be suitably interrupted by cleavage at thin portion 226 of first terminal plate and displacement of center portion 242 of second terminal plate, without first terminal plate 220 and second terminal plate 240 being detached from battery holder 500.

[0101] The safety valve 200 of the present invention cuts off the current by cleaving and separating the first terminal plate 220 as the internal pressure of the battery holder 500 increases. To ensure that such a safety valve 200 operates properly, it is preferable that the battery holder 500 is sealed so that gas does not leak to the outside before the safety valve 200 operates. For example, the battery holder 500 may be sealed by the safety valve 200.

[0102] The adhesive layer 260 disposed on the end surface 510 of the battery holder may be made of a thermoplastic resin. By using a thermoplastic resin as the adhesive layer 260, when the temperature of the battery 1000 becomes abnormally high, the adhesive layer 260 made of a thermoplastic resin is heated, and the fluidity of the adhesive layer 260 increases. Therefore, when the temperature of the battery pack 2000 becomes high and the internal pressure of the battery holder 500 increases, the gas inside the battery holder 500 is released to the outside, pushing aside the adhesive layer 260 made of thermoplastic resin. This allows the internal pressure inside the battery holder 500 to be suitably released.

[0103] In a battery pack in which a plurality of battery holders 500 are connected, the battery holder 500 may include a plurality of openings 550. In such a structure, a safety valve 200 may be disposed in each of the plurality of openings 510. That is, the battery pack may include a plurality of safety valves 200. When a plurality of safety valves 200 are provided, adjacent safety valves 200 may share the second terminal 240. That is, the second terminal 240 may be continuous so as to straddle the adjacent safety valves 200. Alternatively, the second terminals 240 of adjacent safety valves may be electrically connected to each other via a connecting member (not shown).

[0104] 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.

[0105] Note that the embodiment of the present disclosure as described above includes the following preferred aspects. <1> a battery assembly; an exterior body having an opening at one end and housing the battery assembly; and a safety valve disposed in the opening; The safety valve includes an inner terminal located relatively inside and an outer terminal located relatively outside, the inner terminal has a thin-walled portion that is ring-shaped in a plan view on an inner circumferential side relative to an opening end of the opening, and is electrically connected to the battery assembly on an outer circumferential side relative to the thin-walled portion, A battery, wherein the outer terminal is fixed to the inner terminal in a state in which the outer terminal is elastically deformed toward the inside of the outer casing on the inner peripheral side of the thin-walled portion, and the outer terminal and the inner terminal are electrically connected to each other. <2> the thin portion is positioned between a connection portion between the inner terminal and the battery assembly and a fixing portion of the outer terminal at the inner terminal; <1> Battery. <3> the battery assembly and the outer terminal are electrically connected to each other via the thin portion of the inner terminal. <1> or <2> Battery. <4> In a normal state, the opening is sealed by the safety valve. <1> ~ <3> Any of the batteries. <5> The safety valve is provided on the outer side of the exterior body. <1> ~ <4> Any of the batteries. <6> an insulating member disposed between the inner terminal and the outer terminal on an outer circumferential side of the thin-walled portion; <1> ~ <5> Any of the batteries. <7> The insulating member is bonded to each of the inner terminal and the outer terminal on an outer circumferential side of the thin-walled portion. <6> 2. The battery according to claim 1 . <8> The insulating member is bonded to each of the inner terminal and the outer terminal via a thermoplastic resin. <7> 2. The battery according to claim 1 . <9> The exterior body has a side portion continuous with the one end, The insulating member extends to the side portion of the exterior body. <6> 2. The battery according to claim 1 . <10> At the side portion, the exterior body and the insulating member are bonded via a thermoplastic resin. <9> 2. The battery according to claim 1 . <11> The outer terminal has an outer periphery and a central portion surrounded by the outer periphery, The central portion is located relatively closer to the inside of the exterior body than the outer circumferential portion. <1> ~ <10> 13. The battery according to claim 12, <12> a fixing portion for fixing the inner terminal and the outer terminal to each other on the inner peripheral side of the thin-walled portion, The fixed portion is positioned closer to the thin portion than the battery shaft. <1> ~ <11> Any of the batteries. <13> The fixing portion extends continuously along the thinned portion. <12> Battery. <14> A plurality of the fixing portions are provided, In a plan view, the plurality of fixed portions are positioned so as to be point-symmetric with respect to the battery axis. <12> Battery. <15> a non-fixed region in which the inner terminal and the outer terminal are not fixed to each other, the non-fixed region being located on the inner circumferential side of the thin-walled portion; <1> ~ <14> Any of the batteries. <16> The non-fixed region is positioned at the battery axis. <15> Battery. <17> a sealing member disposed between the exterior body and the inner terminal on an outer circumferential side of the thin-walled portion, The sealing member is a thermoplastic resin. <1> ~ <16> 13. The battery according to claim 12, <18> The exterior body has a structure that does not include a beading portion. <1> ~ <17> Any of the batteries. <19> A battery and a battery holder for accommodating the battery, the battery holder includes an opening and a safety valve provided in the opening; the safety valve includes an inner terminal located relatively to the inside of the battery holder and an outer terminal located relatively to the outside of the battery holder, the inner terminal has a thin-walled portion extending radially inward from an opening end of the opening, and is electrically connected to the battery on an outer circumferential side of the thin-walled portion; the outer terminal is fixed to the inner terminal in a state in which the outer terminal is elastically deformed toward the inside of the battery holder on a part more inward than the thin-walled portion. <20> the opening of the battery holder is sealed by the safety valve; <19> Battery pack. <21> the battery holder has an end surface extending to an outer periphery of the opening, The end face is bonded to each of the inner terminal and the outer terminal on an outer circumferential side of the thin-walled portion. <19> or <20> Battery pack. <22> the battery holder includes a plurality of the openings; The safety valve is provided in each of the plurality of openings. <19> ~ <21> One of the battery packs.

[0106] The above effects are merely examples, and the present invention is not limited to the above, and may have additional effects. [Industrial Applicability]

[0107] 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]

[0108] 10 Battery assembly 11 Positive electrode 12 Negative electrode 13 Separator 15 Conductive materials 50 Exterior body 52 Exterior opening 53 Open end of exterior body 54 End face of exterior body 54A Cover material 55 Cylinder 56 Beading section 57 Edge of exterior body 58 Side of exterior body 100 Safety valve 110 Sealing member 120 First terminal (inner terminal) 120a: First surface of first terminal 120b Second surface of first terminal 122 Center of first terminal 124 Outer periphery of first terminal 126 Thin part of first terminal 130 Insulating materials 132 Openings in insulating materials 140 2nd terminal (outer terminal) 140a First surface of second terminal 140b Second surface of second terminal 142 Center of second terminal 144 Outer periphery of second terminal 150 Fixed part 160 Adhesive layer 1000 secondary battery 2000 Battery Pack 200 Safety valve 210 Sealing member 220 1st terminal 222 Center of first terminal 224 Outer periphery of first terminal 226 Thin part of first terminal 230 Insulating materials 232 Openings in insulating materials 240 2nd terminal 242 Center of second terminal 244 Outer periphery of second terminal 250 Fixed part 260 Adhesive layer 500 Battery Holder 510 Battery holder end face 550 Battery holder opening

Claims

1. a battery assembly; an exterior body having an opening at one end and housing the battery assembly; and a safety valve disposed in the opening; The safety valve includes an inner terminal located relatively inside and an outer terminal located relatively outside, the inner terminal has a thin-walled portion that is ring-shaped in a plan view on an inner circumferential side relative to an opening end of the opening, and is electrically connected to the battery assembly on an outer circumferential side relative to the thin-walled portion, A battery, wherein the outer terminal is fixed to the inner terminal in a state in which the outer terminal is elastically deformed toward the inside of the exterior body on the inner peripheral side of the thin-walled portion, and the two are electrically connected to each other.

2. The battery according to claim 1 , wherein the thinned portion is positioned between a connection portion between the inner terminal and the battery assembly and a fixed portion of the outer terminal at the inner terminal.

3. The battery of claim 1 , wherein the battery assembly and the outer terminal are electrically connected to each other through the thinned portion of the inner terminal.

4. 2. The battery of claim 1, wherein in a normal state, the opening is sealed by the safety valve.

5. The battery according to claim 1 , wherein the safety valve is provided on the exterior side of the exterior body.

6. The battery according to claim 1 , further comprising an insulating member disposed between the inner terminal and the outer terminal, on an outer peripheral side of the thin-walled portion.

7. The battery according to claim 6 , wherein the insulating member is bonded to each of the inner terminal and the outer terminal on an outer circumferential side of the thin-walled portion.

8. The battery according to claim 7 , wherein the insulating member is bonded to each of the inner terminal and the outer terminal via a thermoplastic resin.

9. The exterior body has a side portion continuous with the one end, The battery of claim 6 , wherein the insulating member extends to the side of the exterior body.

10. The battery according to claim 9 , wherein the exterior body and the insulating member are bonded to each other at the side portions via a thermoplastic resin.

11. The outer terminal has an outer periphery and a central portion surrounded by the outer periphery, The battery according to claim 1 , wherein, in a cross-sectional view, the central portion is located relatively closer to the inside of the exterior body than the outer periphery.

12. a fixing portion for fixing the inner terminal and the outer terminal to each other on the inner peripheral side of the thin-walled portion, The battery of claim 1 , wherein the fixed portion is positioned closer to the thinned portion than the battery axis.

13. The battery of claim 12 , wherein the fixed portion extends continuously along the thinned portion.

14. A plurality of the fixing portions are provided, The battery according to claim 12 , wherein the plurality of fixed portions are positioned so as to be point-symmetric with respect to the battery axis in a plan view.

15. The battery according to claim 1 , further comprising an unfixed region, on an inner circumferential side of the thin-walled portion, where the inner terminal and the outer terminal are not fixed to each other.

16. The battery of claim 15 , wherein the non-anchored region is located at the battery axis.

17. a sealing member disposed between the exterior body and the inner terminal on an outer circumferential side of the thin-walled portion, The battery according to claim 1 , wherein the sealing member is a thermoplastic resin.

18. The battery according to claim 1 , wherein the exterior body has a structure that does not include a beading portion.

19. A battery and a battery holder for accommodating the battery, the battery holder includes an opening and a safety valve provided in the opening; the safety valve includes an inner terminal located relatively to the inside of the battery holder and an outer terminal located relatively to the outside of the battery holder, the inner terminal has a thin-walled portion extending radially inward from an opening end of the opening, and is electrically connected to the battery on an outer circumferential side of the thin-walled portion; the outer terminal is fixed to the inner terminal in a state in which the outer terminal is elastically deformed toward the inside of the battery holder on a portion inner than the thin-walled portion.

20. 20. The battery pack of claim 19, wherein the opening of the battery holder is sealed by the safety valve.

21. the battery holder has an end surface extending to an outer periphery of the opening, The battery pack according to claim 19 , wherein the end face is disposed on an outer circumferential side of the thin-walled portion, between the inner terminal and the outer terminal.

22. the battery holder includes a plurality of the openings; The battery pack according to claim 19 , wherein each of the plurality of openings is provided with a safety valve.

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