Secondary battery

Abstract

In one embodiment of the present invention, a secondary battery is provided, in which an electrode assembly and an electrolyte are sealed in an outer body, the electrode assembly includes a positive electrode, a negative electrode and a separator arranged between the positive electrode and the negative electrode, in the above-mentioned secondary battery, there is a separator positioned between the electrode assembly and the outer body, the electrode assembly has a positive electrode collector ear and a negative electrode collector ear protruding from the electrode assembly, when viewed from above, the separator has a first recess for the positive electrode collector ear and a second recess for the negative electrode collector ear at the outer edge, and the first recess and the second recess are arranged with a separator between them.

Description

Technical Field

[0001] The present invention relates to a secondary battery. Background Art

[0002] Secondary batteries are so-called storage batteries, and therefore can be repeatedly charged and discharged, and are used for various purposes. For example, secondary batteries are used in mobile devices such as mobile phones, smartphones, and notebook personal computers.

[0003] A secondary battery generally has a structure in which an electrode assembly is housed in an outer casing. In other words, in a secondary battery, an electrode assembly is housed in an outer casing serving as a case.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-224094

[0005] Patent Document 2: Japanese Patent Application Publication No. 2015-162274

[0006] The inventors of the present application have noticed that there are problems that should be overcome in conventional secondary batteries, and have found that measures need to be taken to overcome these problems. Specifically, the inventors of the present application have found that there are the following problems.

[0007] A secondary battery generally has a structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator disposed therebetween, and an electrolyte are enclosed in an outer casing. The electrode assembly has a positive electrode collector tab and a negative electrode collector tab protruding from the electrode assembly. In addition, a spacer for insulating the electrode assembly and the outer casing is provided between the electrode assembly and the outer casing (for example, Patent Document 1).

[0008] exist Fig.11 In the illustrated embodiment, the positive electrode collector tab 61 and the negative electrode collector tab 62 protrude from the end surface 200' of the electrode assembly 200 (see Fig.11 (A)). A spacer 4 is provided between such an end face 200' and an outer casing (not shown). The spacer 4 is provided with two hollow portions 8 for respectively passing the positive electrode collector tab 61 and the negative electrode collector tab 62 (see Fig.11 (B)).

[0009] The strength of the portion around the through opening 8 of the spacer 4 may be greatly reduced, so there is a concern that such a portion may be deformed and / or damaged when the battery is subjected to impact or heat, etc. Therefore, there is a concern that the collector tabs of the positive and negative electrodes may contact and short-circuit. Summary of the invention

[0010] The present invention has been made in view of such problems. That is, a main object of the present invention is to provide a secondary battery that is more suitable in terms of short circuit prevention.

[0011] The present invention relates to a secondary battery, in which an electrode assembly and an electrolyte are sealed in an outer body, wherein the electrode assembly includes a positive electrode, a negative electrode, and an electrode assembly of a separator arranged between the positive electrode and the negative electrode. In the above-mentioned secondary battery, there is a separator positioned between the electrode assembly and the outer body, and the electrode assembly has a positive electrode collector ear and a negative electrode collector ear protruding from the electrode assembly. When viewed from above, the separator has a first recess for the positive electrode collector ear and a second recess for the negative electrode collector ear at the outer edge, and the first recess and the second recess are arranged with a separator between them.

[0012] The secondary battery according to the present invention has a structure more suitable for preventing short circuits.

[0013] Specifically, in the secondary battery involved in the present invention, the spacer positioned between the electrode assembly and the outer body has a first recess for the positive electrode collector ear and a second recess for the negative electrode collector ear at its outer edge. Through such a recess, one end of the collector ear protruding from the electrode assembly can be positioned toward the outer body without providing a through opening in the spacer. Thus, the reduction in strength around the hollow portion defined by the recess provided in the spacer for the collector ear can be suppressed. Therefore, a short circuit caused by contact between the collector ears of the positive and negative electrodes can be more appropriately prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 (A) and Figure 1 (B) is a schematic cross-sectional view showing an electrode assembly ( Figure 1 (A): non-wound planar stacked battery, Figure 1 (B): wound type battery).

[0015] Figure 2 A schematic perspective development view of a secondary battery according to the present invention is shown.

[0016] Figure 3 A schematic perspective view showing an electrode assembly to which a separator of a secondary battery according to the present invention is attached.

[0017] Figure 4 Schematic plan views showing various aspects of the spacer according to the present invention.

[0018] Figure 5 A schematic perspective assembly diagram of a secondary battery according to the present invention is shown.

[0019] Figure 6 Indicates along Figure 5 A schematic cross-sectional view of a secondary battery taken along line a-a'.

[0020] Figure 7 Indicates along Figure 5 A schematic cross-sectional view of the secondary battery taken along line bb'.

[0021] Figure 8 Indicates along Figure 5 Schematic cross-sectional view of the secondary battery taken along line c-c'.

[0022] Fig. 9 A schematic perspective view for explaining structural members constituting an electrode assembly of a secondary battery according to the present invention is shown.

[0023] Fig.10 (A) and Fig.10 (B) is a schematic perspective view for explaining a method for assembling electrodes constituting the secondary battery according to the present invention.

[0024] Fig.11 (A) and Fig.11 (B) is a schematic diagram showing a structural member of a secondary battery according to the prior art ( Fig.11 (A): electrode assembly, Fig.11 (B): spacer). DETAILED DESCRIPTION

[0025] The secondary battery according to one embodiment of the present invention is described in more detail below. The description will be made with reference to the drawings as needed, but the various elements of the drawings are only schematically and exemplarily shown for understanding the present invention, and the appearance, dimensional ratio, etc. may be different from the actual object.

[0026] In this specification, "cross-sectional observation of a secondary battery" is based on a hypothetical cross section of an object obtained by cutting along the thickness direction of the stacking direction of each layer constituting the secondary battery. For example, a cross section is cut along a plane formed by the thickness direction of the stacking direction of the electrode layers constituting the secondary battery and the length direction of the electrode layers extending toward the direction where the electrode terminals are located. In short, based on Figure 6 The cross-sectional morphology of the secondary battery shown in FIG.

[0027] In this specification, "a spacer viewed from above" is a schematic diagram based on a case where an object is viewed from above or below along the thickness direction of the spacer's shape with the smallest dimension. For example, the shape based on a plane formed by the length direction of the spacer's shape with the largest dimension and the width direction with the second largest dimension in such a length direction. In short, based on Figure 4 The planar morphology of the spacer shown in FIG.

[0028] [Basic structure of the secondary battery according to the present invention]

[0029] The present invention provides a secondary battery. In this specification, the term "secondary battery" refers to a battery that can be repeatedly charged and discharged. "Secondary battery" is not limited to its name, and can include, for example, electrochemical devices such as "power storage devices".

[0030] The secondary battery according to the present invention includes an electrode assembly having an electrode constituent unit including a positive electrode, a negative electrode, and a separator. Figure 1 (A) and Figure 1 (B) shows an example electrode assembly 200. As shown in the figure, the positive electrode 1 and the negative electrode 2 are stacked with the separator 3 to form an electrode unit 100. At least one of the electrode units 100 is stacked to form an electrode assembly (see Figure 1 (A), or by winding the electrode to form a unit to form an electrode assembly (refer to Figure 1 (B) In the secondary battery, such an electrode assembly is sealed in an outer casing together with an electrolyte (eg, a non-aqueous electrolyte).

[0031] The positive electrode is composed of at least a positive electrode material layer and a positive electrode collector (for example, a positive electrode collector in a layered form). In the positive electrode, at least one surface of the positive electrode collector is provided with a positive electrode material layer, and the positive electrode material layer contains a positive electrode active material as an electrode active material. For example, the plurality of positive electrodes of the electrode assembly may also be provided with a positive electrode material layer on both surfaces of the positive electrode collector, or may be provided with a positive electrode material layer only on one surface of the positive electrode collector. From the viewpoint of further increasing the capacity of the secondary battery, the positive electrode is preferably provided with a positive electrode material layer on both surfaces of the positive electrode collector.

[0032] The negative electrode is composed of at least a negative electrode material layer and a negative electrode collector (for example, a negative electrode collector in a layered form). In the negative electrode, a negative electrode material layer is provided on at least one surface of the negative electrode collector, and the negative electrode material layer contains a negative electrode active material as an electrode active material. For example, the plurality of negative electrodes of the electrode assembly may also be provided with negative electrode material layers on both surfaces of the negative electrode collector, respectively, or may be provided with a negative electrode material layer only on one surface of the negative electrode collector. From the viewpoint of further increasing the capacity of the secondary battery, the negative electrode is preferably provided with negative electrode material layers on both surfaces of the negative electrode collector.

[0033] The electrode active materials contained in the positive electrode and the negative electrode, namely the positive electrode active material and the negative electrode active material, are substances that directly participate in the transfer of electrons in the secondary battery, and are the main substances of the positive and negative electrodes responsible for charging and discharging, namely the battery reaction. More specifically, ions are generated in the electrolyte due to the "positive electrode active material contained in the positive electrode material layer" and the "negative electrode active material contained in the negative electrode material layer", and such ions move between the positive electrode and the negative electrode to transfer electrons and perform charging and discharging. The positive electrode material layer and the negative electrode material layer are particularly preferably layers that can embed and deintercalate lithium ions. In other words, it is preferably a non-aqueous electrolyte secondary battery in which lithium ions move between the positive electrode and the negative electrode via a non-aqueous electrolyte to charge and discharge the battery. In the case where lithium ions participate in charging and discharging, the secondary battery involved in the present invention is equivalent to a so-called lithium ion battery, and the positive electrode and the negative electrode have layers that embed and deintercalate lithium ions.

[0034] When the positive electrode active material of the positive electrode material layer is composed of, for example, granules, a binder (also referred to as an "adhesive") is preferably included in the positive electrode material layer for sufficient contact between the particles and shape retention. Furthermore, a conductive aid is preferably included in the positive electrode material layer for smooth transfer of electrons that promote battery reactions. Similarly, when the negative electrode active material of the negative electrode material layer is composed of, for example, granules, a binder is preferably included for more sufficient contact between the particles and shape retention, and a conductive aid may also be included in the negative electrode material layer for smooth transfer of electrons that promote battery reactions. In this way, since the positive electrode material layer and the negative electrode material layer are in a form containing multiple components, they can also be referred to as "positive electrode composite layer" and "negative electrode composite layer", etc., respectively.

[0035] The positive electrode active material is preferably a material that helps to embed and de-embed lithium ions. According to this viewpoint, the positive electrode active material is preferably, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material is preferably a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese and iron. In other words, in the positive electrode material layer of the secondary battery involved in this embodiment, it is preferred to include such a lithium transition metal composite oxide as a positive electrode active material. For example, the positive electrode active material is lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or a part of their transition metals replaced by other metals. Such a positive electrode active material may be included as a single species, or it may be included in combination of two or more. In a more preferred embodiment, the positive electrode active material contained in the positive electrode material layer may also be lithium cobaltate.

[0036] As the binder that can be included in the positive electrode material layer, there is no particular restriction, but at least one selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer and polytetrafluoroethylene can be cited. As the conductive aid that can be included in the positive electrode material layer, there is no particular restriction, and at least one selected from carbon black such as thermal cracking carbon black, furnace carbon black, channel carbon black, Ketjen black and acetylene black, graphite, carbon nanotubes or carbon fibers such as vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be cited. In a certain exemplary embodiment, the binder of the positive electrode material layer is polyvinylidene fluoride, and in another exemplary embodiment, the conductive aid of the positive electrode material layer is carbon black. In another exemplary embodiment, the binder and the conductive aid of the positive electrode material layer become a combination of polyvinylidene fluoride and carbon black.

[0037] The thickness of the positive electrode material layer is not particularly limited, but is preferably 1 μm to 300 μm, for example 5 μm to 200 μm. The thickness of the positive electrode material layer is the thickness inside the secondary battery, and the average value of measured values ​​at any 10 locations can be used.

[0038] The negative electrode active material is preferably a material that contributes to the insertion and extraction of lithium ions. From this viewpoint, the negative electrode active material is preferably, for example, various carbon materials, oxides, or lithium alloys.

[0039] As various carbon materials for negative electrode active materials, graphite (such as natural graphite and / or artificial graphite), hard carbon, soft carbon, and / or diamond-like carbon can be cited. In particular, graphite is preferred in terms of high electronic conductivity and excellent adhesion to the negative electrode collector. As oxides for negative electrode active materials, at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, and lithium oxide can be cited. The lithium alloy of the negative electrode active material can be any metal that can form an alloy with lithium, for example, it can be a binary, ternary or more alloy of metals such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La and lithium. Such oxides can also be amorphous as their structural form. This is because it is difficult to cause degradation due to inhomogeneities such as crystal grain boundaries or defects. In a certain exemplary embodiment, the negative electrode active material of the negative electrode material layer is artificial graphite.

[0040] As the binder that can be included in the negative electrode material layer, there is no particular restriction, and at least one selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin and polyamide-imide resin can be cited. In a more preferred embodiment, the binder contained in the negative electrode material layer becomes styrene-butadiene rubber. As the conductive aid that can be included in the negative electrode material layer, there is no particular restriction, but at least one selected from carbon black such as thermal cracking carbon black, furnace black, channel black, Ketjen black and acetylene black, graphite, carbon nanotubes or vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be cited. In addition, the negative electrode material layer can also include a component derived from a thickener component (such as carboxymethyl cellulose) used in battery manufacturing.

[0041] In one exemplary embodiment, the negative electrode active material and the binder of the negative electrode material layer are a combination of artificial graphite and styrene-butadiene rubber.

[0042] The thickness of the negative electrode material layer is not particularly limited, but is preferably 1 μm to 300 μm, for example 5 μm to 200 μm. The thickness of the negative electrode material layer is the thickness inside the secondary battery, and the average of values ​​measured at any 10 locations may be used.

[0043] The positive electrode collector and the negative electrode collector for the positive electrode and the negative electrode are components that help collect or supply electrons generated by the active material due to the battery reaction. Such a collector can be a sheet-like metal component, or it can have a porous or perforated form. For example, the collector can also be a metal foil, a stamped metal, a mesh or an expanded metal, etc. The positive electrode collector for the positive electrode is preferably formed by a metal foil containing at least one selected from the group consisting of aluminum, stainless steel and nickel, such as aluminum foil. On the other hand, the negative electrode collector for the negative electrode is preferably formed by a metal foil containing at least one selected from the group consisting of copper, stainless steel and nickel, such as copper foil.

[0044] The diaphragm is a component provided from the viewpoint of preventing short circuits caused by contact between the positive and negative electrodes and maintaining electrolytes. In other words, the diaphragm can be said to be a component that prevents contact between electrons of the positive electrode and the negative electrode and allows ions to pass through. The preferred diaphragm is a porous or microporous insulating component that has a film shape due to its small thickness. Although it is only an example after all, a microporous film made of polyolefin can also be used as a diaphragm. In this regard, the microporous film used as a diaphragm can also contain only polyethylene (PE) or only polypropylene (PP) as a polyolefin. Furthermore, the diaphragm can also be a laminate composed of a "microporous film made of PE" and a "microporous film made of PP". The surface of the diaphragm can also be covered with an inorganic particle coating layer and / or an adhesive layer. The surface of the diaphragm can also be adhesive.

[0045] The thickness of the separator is not particularly limited, but is preferably 1 μm to 100 μm, for example 5 μm to 20 μm. The thickness of the separator is the thickness inside the secondary battery (particularly the thickness between the positive electrode and the negative electrode), and the average value of the measured values ​​at any 10 locations may also be used.

[0046] In the secondary battery involved in the present invention, the electrode assembly including the positive electrode, the negative electrode and the separator is sealed in an outer body together with the electrolyte. The electrolyte helps the movement of metal ions released from the electrode (positive electrode / negative electrode). The electrolyte can also be a "non-aqueous" electrolyte such as an organic electrolyte and an organic solvent, or it can be an "aqueous" electrolyte containing water. In a certain exemplary embodiment, it becomes a non-aqueous electrolyte secondary battery using an electrolyte containing a "non-aqueous" solvent and a solute as an electrolyte. The electrolyte can have a liquid or gel form (in addition, in this specification, a "liquid" non-aqueous electrolyte is also referred to as a "non-aqueous electrolyte solution").

[0047] As a specific solvent of a non-aqueous electrolyte, at least carbonate is preferably included. Such carbonate may also be cyclic carbonate and / or chain carbonate. Although not particularly limited, as cyclic carbonate, at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC) may be cited. As chain carbonate, at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC) may be cited. In an exemplary embodiment of the present invention, a combination of cyclic carbonate and chain carbonate is used as a non-aqueous electrolyte, for example, a mixture of ethylene carbonate and diethyl carbonate is used. As a specific solute of a non-aqueous electrolyte, for example, Li salts such as LiPF6 and / or LiBF4 may also be used.

[0048] As the collector tab, all collector tabs used in the field of secondary batteries can be used. The collector tab can be made of a material that can realize the movement of electrons, and is usually made of conductive materials such as silver, gold, copper, iron, tin, platinum, aluminum, nickel and / or stainless steel. The shape of the collector tab is not particularly limited, for example, it can be linear, or it can be plate-shaped. The collector tabs on the positive electrode side and the negative electrode side (hereinafter collectively referred to as "positive and negative collector tabs") can also protrude from any surface of the electrode assembly. The positive and negative collector tabs can also protrude from different surfaces of the electrode assembly, or they can protrude from the same surface respectively. From the perspective of miniaturization of secondary batteries, the positive and negative collector tabs preferably protrude from the same surface. In other words, the positive collector tab and the negative collector tab can also extend in a manner that they protrude from the same end surface (i.e., the same side) of the electrode assembly.

[0049] The outer casing is usually a hard shell, and may also be composed of two components such as a main body and a cover. For example, when the outer casing is composed of a main body and a cover, the main body and the cover are sealed after accommodating the electrode assembly, the electrolyte and the collector ear, and the desired electrode terminal, etc. There is no particular limitation on the sealing method of the outer casing, and for example, a laser irradiation method can be cited.

[0050] As the material constituting the main body and the cover of the outer body, all materials that can constitute a hard shell type outer body in the field of secondary batteries can be used. Such a material can also be a conductive material that can realize the movement of electrons, or it can also be an insulating material that cannot realize the movement of electrons. From the perspective of electrode removal, the material of the outer body is preferably a conductive material.

[0051] As the conductive material, for example, there can be mentioned conductive materials such as silver, gold, copper, iron, tin, platinum, aluminum, nickel and / or stainless steel. As the insulating material, for example, there can be mentioned insulating polymer materials such as polyester (for example, polyethylene terephthalate), polyimide, polyamide, polyamide-imide, and / or polyolefin (for example, polyethylene and / or polypropylene).

[0052] From the viewpoint of the above-mentioned conductivity and rigidity, the main body and the cover may be both made of stainless steel. In addition, as defined in "JIS G 0203 Steel Terminology", stainless steel is an alloy steel containing chromium or chromium and nickel, and generally refers to steel having a chromium content of about 10.5% or more of the total. Examples of such stainless steel include martensitic stainless steel, ferritic stainless steel, austenitic stainless steel, austenitic-ferritic stainless steel and / or precipitation hardening stainless steel.

[0053] The dimensions of the main body and the cover of the outer casing are mainly determined by the dimensions of the electrode assembly. For example, the outer casing may have dimensions that prevent the electrode assembly from moving inside the outer casing when the electrode assembly is housed. By preventing the movement of the electrode assembly, damage to the electrode assembly caused by impact or the like can be prevented, thereby improving the safety of the secondary battery.

[0054] The outer body may also be a flexible shell such as a bag made of a laminated film. The laminated film is a structure having at least a metal layer (such as aluminum) and an adhesive layer (such as polypropylene and / or polyethylene), and may also be a structure having an additional protective layer (such as nylon and / or polyamide).

[0055] The thickness of the outer casing (ie, the wall thickness) is not particularly limited, but is preferably 10 μm to 200 μm, for example 50 μm to 100 μm. The thickness of the outer casing may be the average of values ​​measured at any 10 locations.

[0056] Secondary batteries are usually provided with electrode terminals. Such electrode terminals may also be provided on at least one surface of the outer body. For example, a positive electrode terminal and a negative electrode terminal may be provided separately from each other on the same surface of the outer body. Alternatively, the positive and negative electrode terminals may be provided separately so that the positive electrode terminal and the negative electrode terminal are on different surfaces of the outer body. From the perspective of miniaturization of the secondary battery, the positive electrode terminal and the negative electrode terminal may also protrude from the same surface. Specifically, the electrode terminals on the positive side and the negative side may protrude from the side of the outer body in a manner protruding in a direction perpendicular to the direction in which the electrode layers are stacked.

[0057] The electrode terminal is preferably made of a material having high electrical conductivity. The material of the electrode terminal is not particularly limited, but may be at least one selected from the group consisting of silver, gold, copper, iron, tin, platinum, aluminum, nickel, and stainless steel.

[0058] The electrode terminal may be made of a single material or a plurality of materials. The electrode terminal made of a plurality of materials (hereinafter also referred to as an "electrode terminal structure") is composed of a rivet portion, an inner terminal, and a washer portion.

[0059] The rivet portion and the inner terminal may be made of a material that enables the movement of electrons. For example, the rivet portion and the inner terminal may be made of conductive materials such as silver, gold, copper, iron, tin, platinum, aluminum, nickel, and / or stainless steel, respectively. The gasket portion may be made of an insulating material. For example, the gasket portion may be made of an insulating polymer material such as polyester (e.g., polyethylene terephthalate), polyimide, polyamide, polyamide-imide, and / or polyolefin (e.g., polyethylene and / or polypropylene).

[0060] The collector tabs of the positive and negative electrodes are electrically connected to the electrode terminals or electrode terminal structures, and are electrically conducted to the outside through the electrode terminals or electrode terminal structures.

[0061] The electrode terminal structure is not particularly limited, but for example, it can be embedded and inserted into the through hole of the outer body. Alternatively, the electrode terminal structure mainly includes: a conductive rivet part for leading the electrode to the outside; an outer gasket part for ensuring electrical insulation between such rivet part and the outer body and preventing leakage of electrolyte; an inner terminal for ensuring electrical connection between the rivet part and the collector ear; and an inner gasket part for ensuring electrical insulation between such inner terminal and the outer body and preventing leakage of electrolyte.

[0062] The collector ears of the positive and negative electrodes may also be connected to the electrode terminals or electrode terminal structures. In addition, the collector ears of the positive and negative electrodes may be electrically connected to the outer casing and led to the outside through such an outer casing. For example, in the case where the outer casing is a conductive hard shell type outer casing, the collector ears may also be electrically connected to the inner side of the outer casing by contact, or may be led to the outside through such an outer casing. In other words, the outer casing may also carry the charge of the positive or negative electrode by connecting to the collector ears, and the collector ears may also be electrically led to the outside from the electrode terminals provided on the outer casing.

[0063] From the perspective of miniaturization and voltage balance of the secondary battery, the collector tab of one of the positive and negative electrodes may be electrically connected to the electrode terminal structure, and the collector tab of the other electrode may be electrically connected to the inside of the conductive hard shell type outer casing.

[0064] As a spacer, all spacers used in the field of secondary batteries can be used. For example, as long as the spacer prevents the contact of electrons between the electrode assembly (especially the electrode) and the outer body (especially the electrode terminal), there is no particular limitation. Therefore, the spacer can also be referred to as an insulating member that prevents the contact of electrons between the electrode assembly and the outer body (especially its electrode terminal). The spacer as a whole can also be plate-shaped, for example. As a material constituting the spacer, in addition to polymer materials such as polyolefins (such as polyethylene and / or polypropylene), polystyrene, polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyvinyl chloride, acrylic polymers (such as polymethyl methacrylate, etc.) and / or polycarbonates, various insulating materials such as rubber materials such as nitrile rubber, polyurethane rubber, fluororubber and / or silicone rubber can also be cited. As long as the spacer can prevent the contact between the electrode assembly and the outer body, it can have any form, for example, it can also have the form of a film, a sheet, a plate or a fabric (such as a non-woven fabric).

[0065] [Features of the secondary battery according to the present invention]

[0066] A secondary battery according to one embodiment of the present invention is a battery including an electrode assembly and an exterior body that houses the electrode assembly, and the shape of a separator disposed in the exterior body is characteristic.

[0067] Specifically, in the secondary battery according to one embodiment of the present invention, the separator has a first recess for the positive electrode collector tab and a second recess for the negative electrode collector tab at the outer edge when viewed from above. Figure 2In the illustrated embodiment, the secondary battery has a spacer 4 positioned between the electrode assembly 200 and the outer casing 300 (310) inside the outer casing 300 (310), and the spacer 4 has a first recess 41 for the positive electrode collector tab 61 and a second recess 42 for the negative electrode collector tab 62 at the outer edge.

[0068] By means of such recessed portions 41 and 42, one end of the positive electrode collector tab 61 and the negative electrode collector tab 62 protruding from the electrode assembly 200 can be positioned toward the outer body side (i.e., the electrode terminals 51 and 52 side) without using an opening portion penetrating the spacer 4. In the case of the penetrating opening portion, the positive electrode collector tab and the negative electrode collector tab are completely surrounded by the contour surface of the recessed portion 41 and the recessed portion 42, respectively, when viewed in cross section or in plan. Therefore, since a space is formed by the opening shape, the upper side portion and the bottom side portion of the mutually spaced and opposed contour of the opening portion are easily deformed to be close to each other due to an impact from the outside.

[0069] In contrast, in the case of the recessed portion, only a portion of the positive electrode collector tab and only a portion of the negative electrode collector tab are respectively surrounded by the contour surfaces of the recessed portion 41 and the recessed portion 42 when viewed in cross section or in plan view. Specifically, only a portion of the contour of the positive electrode collector tab and only a portion of the contour of the negative electrode collector tab are respectively surrounded by the contour surfaces of the recessed portion 41 and the recessed portion 42 when viewed in cross section or in plan view.

[0070] In other words, when viewed in cross section or in plan view, the positive electrode collector tab 61 and the negative electrode collector tab 62 are respectively formed so as not to be entirely surrounded by the contour surfaces of the recessed portions 41 and 42. Specifically, when viewed in cross section or in plan view, the entire contour of the positive electrode collector tab 61 and the entire contour of the negative electrode collector tab 62 are respectively formed so as not to be entirely surrounded by the contour surfaces of the recessed portions 41 and 42.

[0071] According to such a structure, since the upper side portion of the mutually spaced and opposed contours that are opposed to the bottom side does not exist, the upper side portion and the bottom side portion of the mutually spaced and opposed contours of the opening portion cannot approach each other due to external impact or the like. As a result, deformation and / or damage of the recessed portion are less likely to occur. As a result, the strength reduction of the solid portion of the spacer 4 around the hollow portion formed by the contour of the recessed portion provided in the spacer 4 for the collector tabs 61 and 62 can be suppressed. Therefore, deformation and / or damage around such a hollow portion can be prevented, and a short circuit caused by contact between the collector tabs 61 and 62 can be more appropriately prevented.

[0072] In addition, in the spacer, the first recess and the second recess are provided across the partition. In other words, the first recess and the second recess are not connected to each other and are provided separately. Here, the "partition" refers to the solid part of the spacer positioned between the first recess and the second recess, that is, the continuous part constituting a part of the spacer.

[0073] exist Figure 2 In the illustrated embodiment, in the spacer 4, the first recess 41 and the second recess 42 are provided across the partition. The recesses 41 and 42 are provided across the partition so that the collector tabs can be accommodated in each recess, thereby preventing the positive collector tab 61 and the negative collector tab 62 from being displaced. This can particularly prevent a short circuit of the secondary battery. In addition, in the spacer 4, there is a portion where the collector tab is provided.

[0074] The "recess for the collector tab" in the present disclosure refers to a recess that can accommodate and arrange the collector tab. For example, it means that the collector tab can cross the recess and / or the collector tab can be fitted (or fixed) in the recess.

[0075] exist Figure 3 , Figure 7 as well as Figure 8 In the illustrated embodiment, the positive electrode collector tab 61 crosses the first recess 41, and the negative electrode collector tab 62 crosses the second recess 42. In other words, the positive electrode collector tab 61 extends through the first recess 41, and the negative electrode collector tab 62 extends through the second recess 42. Thus, the positive electrode collector tab 61 and the negative electrode collector tab 62 can extend from one side of the separator 4 (i.e., the electrode assembly 200 side) to the other side (i.e., the electrode terminals 51, 52 side).

[0076] The "recess" disclosed herein refers to a depression (or height difference) in the same plane. The profile of the recess when the secondary battery is observed in cross section may be curved, linear, or a combination thereof. From the perspective of improving strength, it is preferred that the recess profile is curved at the corners of the recess and is linear at the bottom of the recess.

[0077] In the spacer according to the present invention, by making the hollow portion for setting the collector tab into a recessed portion, the area of ​​such a hollow portion can be reduced compared to the case where it is a through opening. In addition, the shape of the corner of the hollow portion can be formed with a large curvature radius, and a structure that is less likely to cause stress concentration can be achieved. Therefore, it is possible to suppress the reduction in strength around the hollow portion provided in the spacer for the collector tab.

[0078] From the viewpoint of further suppressing the reduction in strength of the peripheral portion of the recess, it is preferred that the first recess and the second recess have a smaller height difference. Specifically, the ratio of the width dimension (T1 and T2) of the solid portion of the spacer 4 that becomes the first recess 41 and the second recess 42 to the width (or thickness) dimension T0 of the partition between the first recess and the second recess is 0.50 or more and 0.99 or less (see Figure 3 By making such a ratio less than 0.99, the collector ear can more easily cross the recess. By making such a ratio greater than 0.50, the area of ​​the hollow portion can be reduced, and the strength reduction of the peripheral portion of a recess can be more effectively suppressed.

[0079] The first recess and the second recess preferably have a corner shape with a larger curvature radius. Specifically, the curvature radius of the corners of the first recess and the second recess is preferably 20% or more and 180% or less relative to the width dimension of the notch portion that becomes the first recess 41 and the second recess 42. If such a curvature radius is within such a range, it is possible to ensure a space for the collector lug and reduce stress concentration on the peripheral portion of the recess.

[0080] The parameters related to the shape of the collector tab described above may refer to dimensions measured using a micrometer (Model MDH-25MB manufactured by Mitsutoyo Corporation) or a height gauge, or values ​​calculated from the dimensions.

[0081] In the plan view of the spacer 4 according to the embodiment of the present invention, from the viewpoint of ensuring at least a space for the collector tab, the first recess 41 and the second recess 42 may not reach the end of the spacer 4 (see Figure 4 (A), etc.), it can also reach the end of the spacer 4 (refer to Figure 4 (B) and Figure 4 (C)). In addition, from the viewpoint of ensuring a space for the collector ear and reducing stress concentration on the peripheral portion of the recess, it is preferred that the first recess 41 and the second recess 42 do not reach the end of the spacer 4 (see Figure 4 (A), etc.). In addition, the first recess 41 and the second recess 42 may be provided on one side of the outer edge of the spacer 4 (ie, on the same plane) (see Figure 4 (A), etc.), may also be provided on two opposite sides of the outer edge of the spacer 4 (see Figure 4 (D)). In the former case, the collector tabs can be positioned at substantially the same height, and therefore, correspondingly, the terminals of substantially the same size can be arranged substantially on the same axis.

[0082] Alternatively, a convex partition portion may be formed by providing two concave shapes of the first concave portion 41 and the second concave portion 42 on one side of the outer edge of the spacer 4 (see Figure 4 (A), etc.), it is also possible that a partition having an S-shaped shape is formed by providing a first recess 41 and a second recess 42 on two opposite sides of the outer edge of the spacer 4, respectively (see Figure 4 (D)).

[0083] In one embodiment, the spacer 4 has a first recess 41 and a second recess 42 on one side of the outer edge facing each other, and the other side of the outer edge facing each other is substantially straight (see FIG. Figure 4 (A), etc.). By making one side of the outer edge of the spacer 4 into a substantially straight line shape, the positioning accuracy relative to the outer body can be improved. As a result, the spacer 4 can be embedded in the outer body. In addition, the generation of local stress concentration can be reduced, and in particular, the reduction in the strength of the spacer can be suppressed.

[0084] In one embodiment, one main surface of the spacer is in contact with the outer casing. This can prevent the position of the spacer from being misaligned, and in particular, can prevent a short circuit.

[0085] In a more preferred embodiment, one main surface of the spacer is in contact with the electrode terminal structure of the outer body. More specifically, in the cross-sectional view of the secondary battery 400, the outer body 300 is provided with an electrode terminal structure 5', and the spacer 4 is in contact with the rivet portion 50 of the electrode terminal structure 5' (or is attached to the rivet portion 50) (see Figure 6 ). With such a structure, it is possible to prevent the spacer 4 and the outer casing 300 from being displaced from each other, and to provide a space between the spacer 4 and the outer casing 300 for the collector tab to extend.

[0086] In a further preferred embodiment, the spacer 4 has an adhesive layer, and the adhesive layer is in contact with the outer body 300 (see Figure 6 ). The spacer 4 is in contact with the outer casing 300 via the adhesive layer, so that the spacer 4 and the outer casing 300 can be prevented from being misaligned.

[0087] In one embodiment, at least one of the positive collector tab and the negative collector tab is in contact with the spacer. By adopting such a structure, the collector tab and the spacer can be fixed, and the positional deviation between them can be further prevented. Specifically, the collector tab 6 (that is, the positive collector tab 61 and / or the negative collector tab 62) is in contact with the spacer 4 in the portion K that has a bent shape (see Figure 7 as well as Figure 8). By making such a portion K a fulcrum, the collector ear 6 can be in elastic contact with the spacer 4, and the impact that may be generated between the electrode assembly 200 and the spacer 4 can be further absorbed. Thus, the deformation and / or damage of the spacer 4 can be prevented. Here, the "bent shape" refers to a shape that bends from a certain direction to a direction opposite to the direction (for example, a shape that bends in an arch shape).

[0088] In one embodiment, the adhesive layer provided on the main surface of the spacer 4 on the side of the outer casing 300 is in contact with the rivet portion 50 of the electrode terminal structure 5' (see Figure 6 ). In addition, one end of the positive electrode collector tab 61 extending toward the outer casing 300 is attached to the inner terminal 51 (see Figure 7 Similarly, one end of the negative electrode collector tab 62 extending toward the outer casing 300 is attached to a position corresponding to the negative electrode terminal 52 inside the outer casing 300 (see Figure 8 ). With such a structure, the spacer and the collector tab are respectively fixed to the outer casing, and positional deviation therebetween can be further prevented.

[0089] In one embodiment, at least one of the positive electrode collector tab and the negative electrode collector tab extends from the electrode assembly side to the outer casing side in a manner that spans both sides of the main surface of the separator. In the illustrated example, the collector tabs 61 and 62 extend across the separator 4 toward the outer casing 300 (see FIG. Figure 7 as well as Figure 8 Here, "extending across both sides of the main surface of the spacer" means extending to both sides of the main surface of the spacer 4 to at least 1 / 4 of the width of the spacer 4 when the secondary battery 400 is viewed in cross section. In this embodiment, the collector tabs 61 and 62 respectively cross the first recess and the second recess of the spacer 4 and cross the spacer 4. By having such a structure, the collector tabs can interfere with the spacer, and in particular, the positional deviation between them can be prevented.

[0090] In one embodiment, the spacer has a first recess and a second recess on one side of an outer edge when viewed from above, and in the partitioning portion of the spacer, one main surface of the spacer is in contact with the outer casing. Figure 3 In the illustrated embodiment, the spacer 4 contacts the outer casing through the partition between the first recess 41 and the second recess 42 of the spacer 4. By fixing the spacer 4 at the position between the first recess 41 and the second recess 42 (i.e., the partition), the positional deviation of the positive electrode collector tab 61 and the negative electrode collector tab 62 crossing them can be more effectively prevented, and in particular, short circuit can be appropriately prevented.

[0091] In one embodiment, the outer casing 300 has an electrolyte injection port 7 on the same surface where the electrode terminal 5 is provided, and the separator 4 has a third recess 43 corresponding to the injection port 7 (see Figure 2 ). By providing the third recess 43 in the spacer 4, it is possible to prevent damage to the electrode assembly 200 that may occur when the injection nozzle (not shown) is inserted into the injection port 7. More specifically, the position of the injection nozzle can be fixed by the third recess 43, and damage to the injection nozzle caused by collision with the electrode assembly 200 can be prevented. In addition, since there is no intervening object such as a spacer between the injection nozzle and the electrode assembly 200, the electrolyte can be directly injected into the electrode assembly. As a result, the injection speed and the immersion speed can be more effectively increased.

[0092] Alternatively, when the spacer according to the present invention is viewed from above, the third recess 43 of the spacer 4 may be formed on one side of the outer edge where the first recess 41 and the second recess 42 are formed (see FIG. Figure 4 (E) and Figure 4 (F)), it may be formed on the other side opposite to the side where the outer edge of the first recess 41 and the second recess 42 are formed (refer to Figure 4 (G)). From the viewpoint of preventing the positional deviation of the collector tab, in the spacer 4, the third recess 43 is provided with the first recess 41 and the second recess 42 via a partition.

[0093] In one embodiment, the spacer 4 has a first recess 41, a second recess 42, and a third recess 43 on one side of the outer edge facing each other, and the other side of the outer edge facing each other is substantially straight (see FIG. Figure 4 (E) and Figure 4 (F)). By making one side of the outer edge of the spacer 4 into a substantially straight line shape, the positioning accuracy relative to the outer body can be improved. As a result, the spacer 4 can be embedded in the outer body. In addition, the generation of local stress concentration can be reduced, and in particular, the reduction in the strength of the spacer can be suppressed.

[0094] In one embodiment, when the spacer is viewed from above, the outer edge of the spacer forms a shape along the inner edge of the outer casing in addition to the outer edge of the recess. By forming such a structure, the spacer can be embedded in the inner part of the outer casing. In addition, the first recess 41 and the second recess 42 of the spacer 4 can be isolated, and in particular, a short circuit caused by contact between the positive electrode collector ear 61 and the negative electrode collector ear 62 can be appropriately prevented. (See Figure 3 ).

[0095] In one embodiment, the thickness dimension of the spacer involved in the present invention is greater than 100 μm and less than 5 mm. If the thickness dimension is greater than 100 μm, the spacer can be made into a structure with better rigidity and heat resistance. Thus, it can become a spacer that is more difficult to break even when an impact or heat is applied to the secondary battery. If the thickness dimension is less than 5 mm, the secondary battery can be further miniaturized. The thickness dimension of the spacer is preferably greater than 0.15 mm and less than 3 mm, for example, greater than 0.15 mm and less than 1.5 mm.

[0096] In one embodiment, the Young's modulus of the spacer of the present invention is 0.01 GPa or more and 20 GPa or less. If such a Young's modulus is within such a range, the manipulability of the spacer can be maintained, and the rigidity is more excellent. The Young's modulus of the spacer is preferably 1.0 GPa or more and 15 GPa or less, for example, 2.0 GPa or more and 10 GPa or less.

[0097] In one embodiment, the continuous heat-resistant temperature (or continuous use temperature) of the separator involved in the present invention is 60°C or more. If such a continuous heat-resistant temperature is 60°C or more, it can be a separator that is more difficult to deform even when heat is applied to the secondary battery. Preferably, the continuous heat-resistant temperature of the separator is 80°C or more, for example, 100°C or more.

[0098] In one embodiment, the separator according to the present invention includes at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polycarbonate. The separator includes such a composition, so that it can have a structure excellent in rigidity and heat resistance.

[0099] [Method for manufacturing secondary battery according to the present invention]

[0100] The manufacturing method of a secondary battery involved in one embodiment of the present invention includes the following steps. Thus, such a secondary battery can be manufactured. In other words, the manufacturing method of a secondary battery involved in the present invention includes: a step of stacking or winding a positive electrode, a negative electrode, and a separator arranged between the positive electrode and the negative electrode to obtain a precursor of an electrode assembly (electrode assembly step); a step of forming a separator having a first recess and a second recess (a separator formation step); and a step of housing the electrode assembly and the separator in an outer casing, welding the collector ear, and injecting an electrolyte into the outer casing (housing step).

[0101] (Electrode assembly process)

[0102] In this process, if Fig. 9As shown, a positive electrode 1, a negative electrode 2, and a rectangular separator 3 are arranged in a predetermined order and stacked or wound to obtain a precursor of an electrode assembly. Fig.10 As shown in (A), the precursor of the electrode assembly may also be a planar stacked electrode assembly 200 (see Figure 1 (A)). Or Fig.10 As in (B), the precursor of the electrode assembly may be a wound electrode assembly 200 (see Figure 1 (B)). Next, the assembly process of the wound electrode assembly will be described.

[0103] First, a positive electrode 1 having a positive electrode collector tab 61 attached to one side of a positive electrode current collector 11, a negative electrode 2 having a negative electrode collector tab 62 attached to one side of a negative electrode current collector 21, and two rectangular separators 3 are arranged in a predetermined order and wound (see Fig.10 (B)).

[0104] The size of the separator 3 used is not particularly limited as long as the desired electrode assembly can be obtained. For example, the length dimension w1 of the width direction r of the separator 3 is usually preferably 110% or more and 400% or less, for example, 120% or more and 200% or less relative to the winding axial length of the positive electrode 1 or the negative electrode (see Fig. 9 ). Moreover, for example, the length dimension w2 of the length direction s of the separator 3 can also be appropriately determined according to the size of the target secondary battery (particularly the number of windings of the electrode assembly).

[0105] After this step, the precursor of the wound electrode assembly may be pressed in the radial direction of the wound body to be formed into a substantially flat columnar shape as desired.

[0106] (Spacer Forming Step)

[0107] Alternatively, the recessed shape of the spacer of the secondary battery involved in one embodiment of the present invention is formed by punching a sheet of material in such a manner that the outer edge shape of the desired spacer is obtained by punching. Alternatively, the recessed shape of the spacer is formed by providing a notch from the outer edge of the spacer formed into a substantially straight shape. Alternatively, the recessed shape of the spacer can also be formed by injection molding in which a heated molten material is injected into a mold having a desired mold frame shape and cooled and solidified.

[0108] In a preferred embodiment, a sheet-shaped material is formed by punching to provide a spacer having a first recess, a second recess, and / or a third recess. By forming such a structure, the spacer involved in the present invention can be easily manufactured at low cost. The manufacturing process of the spacer based on the punching process is described below.

[0109] First, a sheet of polyethylene terephthalate material (thickness: 0.188 mm) is mounted on a rotary or punching cutting device. Next, the polyethylene terephthalate material is punched using a punching knife (e.g., a Pinnacle (registered trademark) knife) configured to sequentially form the first recess 41, the second recess 42, and the third recess 43 on the same side. Thereafter, unnecessary portions are removed to obtain a spacer 4 (see FIG. 4 ) having the first recess 41, the second recess 42, and the third recess 43. Figure 4 (E)).

[0110] (Storage process)

[0111] The electrode assembly 200 and the separator 4 obtained in the previous step are housed in the outer casing 300, the collector tabs 61 and 62 are welded to the electrode terminals 5, and the electrolyte is injected into the outer casing 300 through the injection port 7 (see Figure 2 Hereinafter, a case where the outer casing 300 is composed of the outer casing main body 310 and the outer casing cover 320 and the electrode terminal 5 and the electrode terminal structure 5 ′ are provided on one surface of the outer casing 300 will be described in detail.

[0112] First, if Figure 7 as well as Figure 8 As shown, the collector tabs 61 and 62 are temporarily bent and shaped so as to extend from the electrode assembly 200 side to the outer casing 300 side across both sides of the main surface of the separator 4 , and then respectively cross the first and second recesses of the separator 4 .

[0113] Next, the electrode assembly 200 and the separator 4 are housed in the outer casing main body 310 (see Figure 2 At this time, the adhesive layer (not shown) provided on the main surface of the spacer 4 on the side of the outer casing 300 is attached to the rivet portion 50 (see Figure 6 ). In addition, one end of the positive electrode collector tab 61 extending toward the outer casing 300 is welded to the inner terminal 51 (see Figure 7 Similarly, one end of the negative electrode collector tab 62 extending toward the outer casing 300 is welded to a position corresponding to the negative electrode terminal 52 inside the outer casing 300 (see Figure 8 ).

[0114] Next, the outer body main body 310 and the outer body cover 320 are welded. Finally, the electrolyte is injected from the injection port 7, and the injection port 7 is closed with a sealing plug (not shown). Welding can be achieved by any method known in the field of secondary batteries, for example, laser irradiation can also be used.

[0115] Although the embodiments of the present invention have been described above, these are merely typical examples, and the present invention is not limited thereto, and a person skilled in the art can easily understand that there are various embodiments within the scope of the present invention.

[0116] Industrial Applicability

[0117] The secondary battery involved in the present invention can be used in various fields where electricity storage is assumed. Although it is only an example, the secondary battery can be used in the electrical, information, and communication fields using mobile devices (for example, including mobile phones, smart phones, notebook personal computers, digital cameras, activity meters, ARM-based computers, electronic paper and other mobile devices); household / small industrial uses (for example, power tools, golf carts, household / nursing / industrial robots); large industrial uses (for example, forklifts, elevators, and port cranes); transportation system fields (for example, hybrid vehicles, electric vehicles, buses, trams, electric power-assisted bicycles, electric two-wheeled vehicles, etc.), power system uses (for example, various power generation, load regulators, smart grids, ordinary household installation type power storage systems, etc.); medical uses (medical equipment fields such as hearing aids and headphones), pharmaceutical uses (dosage management systems, etc.); and IoT fields, space / deep sea uses (for example, space probes, diving research vessels, etc.).

[0118] The secondary battery of the present invention can prevent short circuits that may occur when impact or heat is applied to the battery. Therefore, the secondary battery of the present invention can be preferably used in mobile devices that may be subjected to impact or heat from all directions.

[0119] Description of Reference Numerals

[0120] 1: Positive electrode

[0121] 11: Positive electrode collector

[0122] 12: Positive electrode material layer

[0123] 2: Negative electrode

[0124] 21: Negative electrode collector

[0125] 22: Negative electrode material layer

[0126] 3: Diaphragm

[0127] 4: Spacer

[0128] 41: 1st concave part

[0129] 42: 2nd concave part

[0130] 43: 3rd concave part

[0131] 5: Electrode terminal

[0132] 51: Positive terminal

[0133] 52: Negative terminal

[0134] 5': Electrode terminal structure

[0135] 50: Rivet Department

[0136] 51: Inner terminal

[0137] 52: Washer

[0138] 6: Collector ear

[0139] 61: Positive collector ear

[0140] 62: Negative collector ear

[0141] 63: Insulation

[0142] 7: Electrolyte injection port

[0143] 8: Through opening

[0144] 100: Electrode component

[0145] 200: Electrode assembly

[0146] 200': The protruding end face of the collector ear

[0147] 300: Exterior body

[0148] 310: Main part of outer body

[0149] 320: External body cover

[0150] 400: Secondary battery.

Claims

1. A secondary battery, wherein an electrode assembly and an electrolyte are enclosed in an outer body, wherein the electrode assembly includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, The secondary battery includes a separator positioned between the electrode assembly and the outer casing. The electrode assembly has a positive electrode collector tab and a negative electrode collector tab protruding from the electrode assembly. When viewed from above, the spacer has a first recess for the positive electrode collector ear and a second recess for the negative electrode collector ear at the outer edge, the first recess and the second recess are arranged with a partition between them, the positive electrode collector ear and the negative electrode collector ear respectively cross the first recess and the second recess, and extend from one side of the spacer to the other side, the positive electrode collector ear and the negative electrode collector ear have a portion forming a curved shape, and the portion forming the curved shape between the electrode assembly and the spacer is in contact with the spacer.

2. The secondary battery according to claim 1, wherein In cross-sectional view or plan view, only a portion of the positive electrode current collector tab and only a portion of the negative electrode current collector tab are surrounded by the contour surfaces of the first recess and the second recess.

3. The secondary battery according to claim 1 or 2, wherein: The positive electrode current collector tab and the negative electrode current collector tab are formed so as not to be entirely surrounded by the contour surfaces of the first recess and the second recess, respectively, in cross-sectional view or plan view.

4. The secondary battery according to claim 1 or 2, wherein: The ratio of the width dimension of the solid portion of the spacer forming the first recess and the second recess to the width dimension of the partition is 0.50 or more and 0.99 or less.

5. The secondary battery according to claim 1 or 2, wherein: The spacer has the first recessed portion and the second recessed portion on one opposing side of an outer edge in a plan view, and the other opposing side of the outer edge is in a substantially linear shape.

6. The secondary battery according to claim 1 or 2, wherein: One main surface of the spacer is in contact with the exterior body.

7. The secondary battery according to claim 6, wherein One main surface of the separator is in contact with the electrode terminal structure of the exterior body.

8. The secondary battery according to claim 6, wherein The spacer has an adhesive layer, and the adhesive layer is in contact with the exterior body.

9. The secondary battery according to claim 6, wherein The spacer has the first recess and the second recess on one side of an outer edge in a plan view, and one main surface of the spacer is in contact with the exterior body in the partition portion of the spacer.

10. The secondary battery according to claim 1 or 2, wherein: In a cross-sectional view of the secondary battery, at least one of the positive electrode current collector tab and the negative electrode current collector tab extends from one side to the other side of the separator so as to straddle both sides of the main surface of the separator.

11. The secondary battery according to claim 1 or 2, wherein: The outer casing has an inlet for injecting the electrolyte on the same surface where the electrode terminal is provided, and the separator further has a third recess corresponding to the inlet.

12. The secondary battery according to claim 11, wherein The spacer has the first recessed portion, the second recessed portion, and the third recessed portion on one opposing side of an outer edge in a plan view, and the other opposing side of the outer edge is in a substantially linear shape.

13. The secondary battery according to claim 1 or 2, wherein: When the spacer is viewed from above, the outer edge of the spacer, excluding the outer edge forming the recessed portion, has a shape that follows the inner edge of the exterior body.

14. The secondary battery according to claim 1 or 2, wherein: The positive electrode and the negative electrode are capable of inserting and extracting lithium ions.

15. The secondary battery according to claim 1 or 2, which is used for mobile equipment.

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