Current collector, energy storage element, and energy storage module

Abstract

The collector of the present invention comprises: a resin layer having a first surface and a second surface facing the opposite side of the first surface; a first metal layer located on the first surface of the resin layer; and a second metal layer located on the second surface of the resin layer, wherein the first metal layer has a first opening.

Description

Technical Field

[0001] The present invention relates to a current collector, an electricity storage element, and an electricity storage module. Background Art

[0002] Lithium-ion secondary batteries are widely used as power sources for mobile devices such as mobile phones and notebook computers, hybrid vehicles, etc. As these fields develop, lithium-ion secondary batteries are required to have higher performance.

[0003] For example, a resin current collector is described in Patent Document 1. The resin current collector is composed of a resin layer and metal layers formed on both surfaces thereof. A secondary battery using the resin current collector has a high output density per unit weight.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2019 / 031091 Summary of the Invention

[0007] Technical problem to be solved by the invention

[0008] The electricity generated inside the battery is output to the outside through tabs connected to the current collector. Tabs are connected to the current collector by bonding, welding, screwing, or other methods. The resin layer of a resin current collector is weaker than metal, and connecting the tabs can damage the resin layer, causing a short circuit between the two metal layers sandwiching the resin layer.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a current collector and a storage element that are less likely to short-circuit, and a storage module using the same.

[0010] Technical means for solving technical problems

[0011] In order to solve the above technical problems, the following technical means are provided.

[0012] (1) A current collector of the first embodiment comprises: a resin layer having a first surface and a second surface facing the opposite side of the first surface; a first metal layer located on the first surface of the resin layer; and a second metal layer located on the second surface of the resin layer, wherein the first metal layer has a first opening.

[0013] (2) The current collector of the above aspect may be configured such that the first opening is located opposite to a metal plate bonding portion of the second metal layer, and the second metal layer is bonded to a metal plate for electrical connection to the outside at its metal plate bonding portion.

[0014] (3) The current collector of the above aspect may be configured such that the first metal layer includes a first region and a second region, and the first region and the second region are separated from each other by the first opening.

[0015] (4) The current collector of the above aspect may be configured such that the second metal layer has a second opening.

[0016] (5) The current collector of the above aspect may be configured such that the second opening is located opposite to a metal plate bonding portion of the first metal layer, and the first metal layer is bonded to a metal plate for electrical connection to the outside at its metal plate bonding portion.

[0017] (6) The current collector of the above aspect may be configured such that the second metal layer includes a third region and a fourth region, and the third region and the fourth region are separated from each other by the second opening.

[0018] (7) The current collector of the above embodiment may be configured such that the resin layer is 1.0×10 9 Insulation layer with a thickness of Ω·cm or more.

[0019] (8) The current collector of the above embodiment may be configured such that the resin layer includes any one selected from polyethylene terephthalate (PET), polyimide (PI), polyamideimide (PAI), polypropylene (PP), and polyethylene (PE).

[0020] (9) The current collector of the above embodiment may be configured such that each of the first metal layer and the second metal layer is any one selected from the group consisting of aluminum, nickel, stainless steel, copper, platinum, and gold.

[0021] (10) The current collector of the above embodiment may be configured such that the first metal layer and the second metal layer include different metals or alloys.

[0022] (11) The second embodiment of the storage element includes: a current collector of the above embodiment; a first electrode formed on a first surface of the current collector; a second electrode formed on a second surface of the current collector opposite to the first surface; and a diaphragm or a solid electrolyte layer stacked on one surface of the first electrode or the second electrode.

[0023] Effects of the Invention

[0024] The current collector and the energy storage element of the above-described embodiment can suppress short circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the energy storage element according to the first embodiment.

[0026] Figure 2 This is a cross-sectional view of the electrode assembly according to the first embodiment.

[0027] Figure 3 This is a cross-sectional view of the electrode assembly according to the first embodiment when it is developed.

[0028] Figure 4 This is an enlarged cross-sectional view of a characteristic portion of the current collector of the first embodiment.

[0029] Figure 5 It is a plan view (plane view) showing an enlarged characteristic portion of the current collector of the first embodiment.

[0030] Figure 6 It is an enlarged plan view of a characteristic portion of the current collector of the first modification.

[0031] Figure 7 It is an enlarged plan view of a characteristic portion of the current collector of the second modification. DETAILED DESCRIPTION

[0032] The following describes the embodiments in detail with reference to the accompanying drawings. The drawings used in the following description may show characteristic portions in an enlarged manner to facilitate understanding, and the dimensional ratios of the various components may differ from actual dimensions. The materials, dimensions, and other aspects illustrated in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications can be made without departing from the spirit of the present invention.

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0034] The embodiments of the present invention are provided to explain the present invention in detail to those skilled in the art. The following embodiments can be modified into various other aspects, and the scope of the present invention is not limited to the following embodiments.

[0035] In addition, in the following drawings, the thickness and size of each layer are recorded for the convenience of description and clarity of the description, and the same reference numerals in the drawings represent the same elements. The term "and / or" used in this specification includes any one and all combinations of more than one of the listed items.

[0036] The terms used in this specification are used to describe specific embodiments and are not intended to limit the present invention. As described in this specification, a singular form can include multiple forms unless a contextual difference is explicitly indicated. In addition, the term "comprising" as used in this specification refers to the presence of the mentioned shape, number, stage, action, component, element, and / or group thereof, and is not intended to exclude the presence or addition of one or more other shapes, numbers, actions, components, elements, and / or groups.

[0037] Spatially related terms such as “lower,” “down,” “low,” “upper,” “up,” “left,” and “right” are used to facilitate understanding of an element or feature shown in the accompanying drawings and other elements or features. Such spatially related terms are used to facilitate understanding of the present invention through various process states or usage states of the present invention, and are not used to limit the present invention. For example, when the elements or features of the accompanying drawings are reversed, the elements or features described with “lower” or “down” become “upper” or “above.” Therefore, “lower” is a concept that includes “upper” or “down.” In addition, regarding the direction of viewing the elements of the accompanying drawings, there is a situation where “left” and “right” are reversed.

[0038] (First embodiment)

[0039] Figure 1 Schematic diagram of the energy storage element of this embodiment. The energy storage element 200 is, for example, a lithium ion secondary battery which is a type of non-aqueous electrolyte secondary battery. Figure 1 , for easier understanding, the state of the electrode assembly 100 immediately before being housed in the exterior body C is shown.

[0040] The energy storage element 200 includes an electrode body 100 and an outer casing C. The structure of the electrode body 100 will be described later. The electrode body 100 is housed in a storage space K of the outer casing C along with the electrolyte. The electrode body 100 has tabs t1 and t2 for electrical connection to the outside. The tabs t1 and t2 extend from the inside of the outer casing C to the outside.

[0041] The tabs t1 and t2 are made of metal, such as aluminum, copper, nickel, or SUS.

[0042] The tabs t1 and t2 are, for example, rectangular when viewed in the first direction (when viewed in plan from the z direction described later), but are not limited to this shape and various shapes can be adopted.

[0043] The outer casing C seals the electrode assembly 100 and the electrolyte solution therein. The outer casing C is used to suppress leakage of the electrolyte solution to the outside, intrusion of moisture or the like into the electrode assembly 100 from the outside, and the like.

[0044] The outer body C is, for example, a metal laminate formed by coating a polymer film on both sides of a metal foil. The metal foil is, for example, aluminum foil, and the polymer film is, for example, a resin such as polypropylene. The outer polymer film is, for example, polyethylene terephthalate (PET) or polyamide, while the inner polymer film is, for example, polyethylene (PE) or polypropylene (PP). To facilitate welding by heating, the inner polymer film has a lower melting point than the outer polymer film.

[0045] An adhesive layer containing an adhesive substance may also be provided between the outer casing C and the electrode body 100. The outer casing C covers the outermost surface of the electrode body 100. The inner surface of the outer casing C is opposite to the outermost surface of the electrode body 100. The adhesive layer is, for example, located on the surface of the outer casing C opposite to the electrode body 100 (inner surface) or the surface of the electrode body 100 opposite to the outer casing C (outermost surface of the electrode body). The adhesive layer is, for example, a double-sided tape having electrolyte resistance. The adhesive layer may also be, for example, a rubber such as butyl rubber, a saturated hydrocarbon resin, or the like, obtained by forming an adhesive layer of polyisobutylene rubber on a polypropylene substrate. The adhesive layer is used to suppress the movement of the electrode body 100 inside the outer casing C. In addition, even if the adhesive layer is pierced by a metal object such as a nail, a short circuit is suppressed by wrapping the adhesive substance around the metal object such as the nail.

[0046] The electrolyte solution is, for example, a non-aqueous electrolyte solution containing a lithium salt, etc. The electrolyte solution is obtained by dissolving an electrolyte in a non-aqueous solvent, and the non-aqueous solvent may contain a cyclic carbonate and a chain carbonate.

[0047] Cyclic carbonates solvate the electrolyte. Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, and butylene carbonate. Chain carbonates reduce the viscosity of cyclic carbonates. Examples of chain carbonates include diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate. Other chain carbonates, such as methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, 1,2-dimethoxyethane, and 1,2-diethoxyethane, can also be mixed and used. The ratio of cyclic carbonate to chain carbonate is, for example, 1:9 to 1:1 by volume.

[0048] The non-aqueous solvent may be, for example, a cyclic carbonate or a chain carbonate in which a portion of hydrogen is replaced with fluorine. Examples of the non-aqueous solvent include fluoroethylene carbonate and bisfluoroethylene carbonate.

[0049] Electrolytes include, for example, lithium salts such as LiPF6, LiClO4, LiBF4, LiCF3SO3, LiCF3CF2SO3, LiC(CF3SO2)3, LiN(CF3SO2)2, LiN(CF3CF2SO2)2, LiN(CF3SO2)(C4F9SO2), LiN(CF3CF2CO)2, and LiBOB. These lithium salts may be used alone or in combination. From the perspective of ionization, LiPF6 is preferably included as the electrolyte.

[0050] When dissolving LiPF6 in a non-aqueous solvent, the concentration of the electrolyte in the electrolyte is adjusted to, for example, 0.5 to 2.0 mol / L. When the concentration of the electrolyte is 0.5 mol / L or more, the lithium ion concentration of the non-aqueous electrolyte can be sufficiently ensured, making it easy to obtain sufficient capacity during charge and discharge. In addition, by suppressing the concentration of the electrolyte to within 2.0 mol / L, the viscosity of the non-aqueous electrolyte can be suppressed, the mobility of lithium ions can be sufficiently ensured, and sufficient capacity can be easily obtained during charge and discharge.

[0051] When LiPF6 is mixed with other electrolytes, for example, it is also preferred that the lithium ion concentration in the non-aqueous electrolyte be adjusted to 0.5 to 2.0 mol / L, and the lithium ion concentration derived from LiPF6 be 50 mol% or more.

[0052] The non-aqueous solvent may also include, for example, room-temperature molten salt. Room-temperature molten salt is a salt formed by a combination of cations and anions that remains liquid even at temperatures below 100°C. Because room-temperature molten salt is a liquid composed solely of ions, it has strong electrostatic interactions and is non-volatile and non-flammable.

[0053] Examples of the cation components of the room-temperature molten salt include nitrogen-containing nitrogen-based cations, phosphorus-containing cations, sulfur-containing cations, etc. These cation components may be contained alone or in combination of two or more.

[0054] Examples of the nitrogen-based cations include chain or cyclic ammonium cations such as imidazolium cations, pyrrolidinium cations, piperidinium cations, pyridinium cations, and nitrogenium spiro cations.

[0055] Examples of the phosphorus-based cations include chain-shaped or cyclic phosphorus cations.

[0056] Examples of sulfur-based cations include chain or cyclic sulfonium cations.

[0057] As the cationic component, N-methyl-N-propyl-pyrrolidine (P13) is preferred as a nitrogen-based cation in order to provide high lithium ion conductivity and broad redox resistance, particularly when a lithium imide salt is dissolved.

[0058] As the anion component of the room temperature molten salt, AlCl4 can be listed. - , NO2 - , NO3 - , I - , BF4 - , PF6 - , AsF6 - , SbF6 - , NbF6 - , TaF6- , F(HF) 2.3 - , p-CH3PhSO3 - , CH3CO2 - , CF3CO2 - , CH3SO3 - , CF3SO3 - ,(CF3SO2)3C - , C3F7CO2 - , C4F9SO3 - ,(FSO2)2N - (bis(fluorosulfonyl)imide: FSI), (CF3SO2)2N - (bis(trifluoromethanesulfonyl)imide: TFSI), (C2F5SO2)2N-(bis(pentafluoroethanesulfonyl)imide), (CF3SO2)(CF3CO)N - ((Trifluoromethanesulfonyl)(trifluoromethanecarbonyl)imide), (CN)2N - (dicyandiamide), etc. These anion components may be contained alone or in combination of two or more.

[0059] Figure 2 It is a cross-sectional view of the electrode assembly 100 according to the first embodiment. Figure 2 It is a cross section of the electrode body 100 perpendicular to the winding axis direction of the electrode body 100. The electrode body 100 is formed by winding a current collector 10, a positive electrode active material layer 20, a negative electrode active material layer 30, and a separator 40. The electrode body 100 is repeated from the inside of the winding to the outside of the winding in the order of, for example, the separator 40, the negative electrode active material layer 30, the current collector 10, and the positive electrode active material layer 20. The negative electrode active material layer 30 is located on the inside of the winding compared to the positive electrode active material layer 20, for example. When the negative electrode active material layer 30 is located on the inside of the winding, the energy density of the energy storage element 200 becomes higher. This is because the weight of the negative electrode active material layer 30 is often lighter than the weight of the positive electrode active material layer 20, so that even when the negative electrodes are facing each other on the inside of the winding, the loss of weight energy density is small.

[0060] Figure 3 This is a cross-sectional view of the electrode body 100 according to the first embodiment. Figure 3 The left end is the winding center for winding.

[0061] In the unfolded structure of the electrode body 100, the stacking direction of each layer is the z-direction. The direction from the second metal layer 13 toward the first metal layer 12 is the +z-direction, and the direction opposite to the +z-direction is the -z-direction. A direction within the extended surface of the unfolded structure of the electrode body 100 is the x-direction, and the direction orthogonal to the x-direction is the y-direction. The x-direction is, for example, the longitudinal direction of the unfolded structure of the electrode body 100. The y-direction is, for example, the width direction of the unfolded structure of the electrode body 100.

[0062] The electrode body 100 includes a current collector 10, a positive electrode active material layer 20, a negative electrode active material layer 30, and a separator 40. The positive electrode active material layer 20 is formed on the first surface 10a side of the current collector 10. The negative electrode active material layer 30 is formed on the second surface 10b side of the current collector 10. The second surface 10b is the surface of the current collector 10 opposite to the first surface 10a. The current collector 10 includes a first surface 10a and a second surface 20 facing the opposite side of the first surface 10. The positive electrode active material layer 20 is an example of a first active material layer. The negative electrode active material layer 30 is an example of a second active material layer. The separator 40 is in contact with the positive electrode active material layer 20 or the negative electrode active material layer 30. When the electrode body 100 is in a wound state, the separator 40 is located between the positive electrode active material layer 20 and the negative electrode active material layer 30.

[0063] The current collector 10 includes a resin layer 11, a first metal layer 12, and a second metal layer 13. The first metal layer 12 is formed on the first surface 11a side of the resin layer 11. The second metal layer 13 is formed on the second surface 11b side of the resin layer 11. The second surface 11b is the surface opposite to the first surface 11a in the resin layer 11. The first metal layer 12 is, for example, a positive electrode current collector. The second metal layer 13 is, for example, a negative electrode current collector. For example, a positive electrode active material layer 20 is formed on the surface of the first metal layer 12 opposite to the resin layer 11. In this case, the first metal layer 12 and the positive electrode active material layer 20 form a positive electrode. For example, a negative electrode active material layer 30 is formed on the surface of the second metal layer 13 opposite to the resin layer 11. In this case, the second metal layer 13 and the negative electrode active material layer 30 form a negative electrode. The relationship between the first metal layer 12 and the second metal layer 13 is reversed, and the first metal layer 12 may be a negative electrode current collector and the second metal layer 13 may be a positive electrode current collector.

[0064] The resin layer 11 is made of a material having insulating properties. In this specification, insulating properties means a resistance value of 1.0×10 9Ω·cm or greater. Resin layer 11 is, for example, an insulating layer having insulating properties. Resin layer 11 comprises, for example, any one selected from polyethylene terephthalate (PET), polyimide (PI), polyamide-imide (PAI), polypropylene (PP), and polyethylene (PE). Resin layer 11 is not limited to the materials listed above. Resin layer 11 is, for example, a PET film. The thickness of resin layer 11 is, for example, 3 μm to 9 μm, preferably 4 μm to 6 μm.

[0065] The first metal layer 12 and the second metal layer 13 are each selected from aluminum, nickel, stainless steel, copper, platinum, and gold. The first metal layer 12 and the second metal layer 13 are not limited to these materials. The first metal layer 12 and the second metal layer 13 may, for example, comprise different metals or alloys. For example, the first metal layer 12 may be aluminum, and the second metal layer 13 may be copper. The first metal layer 12 and the second metal layer 13 may also be formed of the same material. For example, the first metal layer 12 and the second metal layer 13 may both be aluminum. The specific structures of the first metal layer 12 and the second metal layer 13 will be described later.

[0066] It is preferable that both the first metal layer 12 and the second metal layer 13 are made of aluminum, or that one of the first metal layer 12 and the second metal layer 13 is made of aluminum and the other is made of copper.

[0067] The thicknesses of the first metal layer 12 and the second metal layer 13 may be the same or different. The thicknesses of the first metal layer 12 and the second metal layer 13 are preferably, for example, 0.3 μm to 2 μm, and more preferably 0.4 μm to 1 μm.

[0068] The first metal layer 12 is, for example, thicker than the resin layer 11. When the first metal layer 12 is thicker than the resin layer 11, the gravimetric energy density can be increased and a decrease in flexibility can be suppressed.

[0069] The second metal layer 13 is, for example, thicker than the resin layer 11. When the second metal layer 13 is thicker than the resin layer 11, the gravimetric energy density can be increased and a decrease in flexibility can be suppressed.

[0070] Alternatively, the thickness of the resin layer 11 may be thicker than the sum of the thicknesses of the first metal layer 12 and the second metal layer 13. This configuration further suppresses a decrease in the flexibility of the current collector 10. Furthermore, by increasing the proportion of the low-specific-gravity resin layer 11 in the current collector 10, the gravimetric energy density of the energy storage element using the resin layer 11 can be increased.

[0071] The positive electrode active material layer 20 includes, for example, a positive electrode active material, a conductive additive, and a binder.

[0072] The positive electrode active material can reversibly perform occlusion and release of lithium ions, desorption and intercalation of lithium ions, or doping and dedoping of lithium ions and counter anions.

[0073] Positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2), lithium manganese spinel (LiMn2O4) and lithium nickel oxide (LiNiO2). x Co y Mn z M a O2 (x+y+z+a=1, 0≤x<1, 0≤y<1, 0≤z<1, 0≤a<1, M is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, Cr), lithium vanadium compound (LiV2O5), olivine-type LiMPO4 (wherein M is one or more elements selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, Zr or VO), lithium titanate (Li4Ti5O 12 ), LiNi x Co y Al z Composite metal oxides such as O2 (0.9<x+y+z<1.1), polyacetylene, polyaniline, polypyrrole, polythiophene, polyacene, etc. Furthermore, the positive electrode active material may be a mixture of these.

[0074] A conductive additive is dispersed within the positive electrode active material layer. The conductive additive improves the conductivity between the positive electrode active materials in the positive electrode active material layer. Examples of the conductive additive include carbon powders such as carbon black, carbon nanotubes, carbon materials, fine metal powders such as copper, nickel, stainless steel, and iron, mixtures of carbon materials and fine metal powders, and conductive oxides such as ITO. The conductive additive is preferably a carbon material such as carbon black. If the active material can ensure sufficient conductivity, the positive electrode active material layer 20 may not contain a conductive additive.

[0075] The binder binds the positive electrode active materials in the positive electrode active material layer to each other. A known binder can be used. The binder is, for example, a fluororesin. Fluororesins include, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), etc.

[0076] In addition to the above, the adhesive may be, for example, vinylidene fluoride-hexafluoropropylene fluororubber (VDF-HFP fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene fluororubber (VDF-HFP-TFE fluororubber), vinylidene fluoride-pentafluoropropylene fluororubber (VDF-PFP fluororubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene fluororubber (VDF-PFP-TFE fluororubber), vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene fluororubber (VDF-PFMVE-TFE fluororubber), vinylidene fluoride-chlorotrifluoroethylene fluororubber (VDF-CTFE fluororubber) and other vinylidene fluoride fluororubbers.

[0077] The positive electrode active material layer 20 is, for example, thicker than the current collector 10. By adopting this structure, the capacity and volume energy density of the energy storage device using the current collector 10 can be further improved.

[0078] By increasing the thickness of the positive electrode active material layer 20, which reacts with charge and discharge, compared to the current collector 10, which does not react with charge and discharge, capacity loss within the energy storage device can be further reduced. Furthermore, when the current collector 10 is thicker than the positive electrode active material layer 20, the proportion of the highly flexible current collector 10 increases, reducing the rigidity of the electrode assembly 100 and making it more susceptible to deformation.

[0079] The negative electrode active material layer 30 contains a negative electrode active material and may also contain a conductive additive, a binder, and a solid electrolyte as needed.

[0080] The negative electrode active material can be any compound that can absorb / release ions, and the negative electrode active materials used in known lithium ion secondary batteries can be used. The negative electrode active material is, for example, particles containing the following materials: metallic lithium, lithium alloys, graphite (natural graphite, artificial graphite) that can absorb / release ions, carbon nanotubes, carbon materials such as difficult-to-graphitize carbon, easy-to-graphitize carbon, and low-temperature calcined carbon, semimetals or metals such as aluminum, silicon, tin, and germanium that can be combined with metals such as lithium, and SiO x (0<x<2), amorphous compounds based on oxides such as tin dioxide, lithium titanate (Li4Ti5O 12 )wait.

[0081] As described above, the negative electrode active material layer 30 may contain, for example, silicon, tin, and germanium. Silicon, tin, and germanium may exist as single elements or as compounds. Compounds include alloys, oxides, and the like. For example, when the negative electrode active material is silicon, the negative electrode is sometimes referred to as a Si negative electrode. The negative electrode active material may also be, for example, a mixture of single elements or compounds of silicon, tin, and germanium and a carbon material. An example of a carbon material is natural graphite. In addition, the negative electrode active material may also be configured such that the surface of a single element or compound of silicon, tin, and germanium is covered with carbon. The carbon material and the covering carbon improve the conductivity between the negative electrode active material and the conductive auxiliary agent. When the negative electrode active material layer contains silicon, tin, and germanium, the capacity of the storage element 200 increases.

[0082] As described above, the negative electrode active material layer 30 may also contain lithium, for example. Lithium may be metallic lithium or a lithium alloy. The negative electrode active material layer 30 may be metallic lithium or a lithium alloy. Lithium alloys are, for example, alloys of lithium and one or more elements selected from Si, Sn, C, Pt, Ir, Ni, Cu, Ti, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Sb, Pb, In, Zn, Ba, Ra, Ge, and Al. As an example, when the negative electrode active material is metallic lithium, the negative electrode is sometimes referred to as a Li negative electrode. The negative electrode active material layer 30 may also be a lithium sheet.

[0083] The negative electrode can be manufactured without the negative electrode active material layer 30 and can consist solely of the negative electrode current collector (second metal layer 13). When the energy storage element 200 is charged, metallic lithium is deposited on the surface of the negative electrode current collector. Metallic lithium is simply lithium with deposited lithium ions, and it functions as the negative electrode active material layer.

[0084] The conductive additive and binder can be made of the same materials as those used for the positive electrode active material layer 20. The binder in the negative electrode active material layer 30 may be, in addition to the materials listed for the positive electrode active material layer 20, cellulose, styrene-butadiene rubber, ethylene-propylene rubber, polyimide resin, polyamide-imide resin, acrylic resin, or the like. Cellulose may also be, for example, carboxymethyl cellulose (CMC).

[0085] The negative electrode active material layer 30 is, for example, thicker than the current collector 10. When this structure is satisfied, the capacity and volume energy density of the energy storage element using the current collector 10 are further increased.

[0086] By making the thickness of the negative electrode active material layer 30, which changes with charge and discharge, thicker than the thickness of the current collector 10, which does not change with charge and discharge, capacity loss within the energy storage device can be further reduced. Furthermore, when the thickness of the current collector 10 is thicker than the thickness of the negative electrode active material layer 30, the proportion of the highly flexible current collector 10 increases, thereby reducing the rigidity of the electrode assembly 100 produced using the current collector 100 and making the electrode assembly 100 more susceptible to deformation.

[0087] The separator 40 has, for example, an electrically insulating porous structure. Examples of the separator 40 include a single layer or laminate of a film made of a polyolefin such as polyethylene or polypropylene, a stretched film of a mixture of such resins, or a fiber nonwoven fabric made of at least one constituent material selected from cellulose, polyester fiber, polyacrylonitrile, polyamide, polyethylene, and polypropylene.

[0088] The thickness of the separator 40 is, for example, thicker than the thickness of the resin layer 11. Furthermore, the thickness of the separator 40 is, for example, also thicker than the thickness of the current collector 10. By using a thicker separator, the separator is preferentially insulated, and a short circuit between the first metal layer 12 and the second metal layer 13 that may occur in the current collector 10 can be suppressed.

[0089] A solid electrolyte layer may be provided instead of the separator 40. When the solid electrolyte layer is used, an electrolyte solution is not required. The solid electrolyte layer and the separator 40 may be used together.

[0090] For example, the solid electrolyte has an ionic conductivity of 1.0×10 -8 S / cm or more 1.0×10 -2 S / cm or less ion conductive membrane. Examples of solid electrolytes include polymer solid electrolytes, oxide solid electrolytes, and sulfide solid electrolytes. Examples of polymer solid electrolytes include those obtained by dissolving alkali metal salts in polyethylene oxide polymers. Examples of oxide solid electrolytes include Li 1.3 Al 0.3 Ti 1.7 (PO4)3(NASICON type), Li 1.07 Al 0.69 Ti 1.46 (PO4)3(glass ceramics), Li 0.34 La 0.51 TiO 2.94 (Perovskite type), Li7La3Zr2O 12 (garnet type), Li 2.9 PO 3.3 N 0.46 (amorphous, LIPON), 50Li4SiO4·50Li2BO3 (glass), 90Li3BO3·10Li2SO4 (glass ceramic). Sulfide-based solid electrolytes such as Li3.25 Ge 0.25 P 0.75 S4 (crystal), Li 10 GeP2S 12 (crystal, LGPS), Li6PS5Cl (crystal, argyrodite type), Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 (Crystallization), Li 3.25 P 0.95 S4 (glass ceramic), Li7P3S 11 (glass ceramics), 70Li2S·30P2S5(glass), 30Li2S·26B2S3·44LiI(glass), 50Li2S·17P2S5·33LiBH4(glass), 63Li2S·36SiS2·Li3PO4(glass), 57Li2S·38SiS2·5Li4SiO4(glass).

[0091] Figure 4 It is an enlarged plan view of a characteristic portion of the current collector 10 according to the first embodiment. Figure 5 This is an enlarged cross-sectional view of a characteristic portion of the current collector 10 according to the first embodiment. Figure 5 It is along Figure 4 The cross section of line AA in .

[0092] The first metal layer 12 is connected to a contact t1. The contact t1 is provided, for example, on the surface of the first metal layer 12 opposite to the resin layer 11. The contact t1 is an example of a first metal plate. The second metal layer 13 is connected to a contact t2. The contact t2 is provided, for example, on the surface of the second metal layer 13 opposite to the resin layer 11. The contact t2 is an example of a second metal plate. Contacts t1 and t2 are used for electrical connection to the outside. Contact t1 is connected to the first metal layer 12 by bonding, welding, screwing, etc. Contact t2 is connected to the second metal layer 13 by bonding, welding, screwing, etc. Contact t1 is welded to the first metal layer 12 and the second metal layer 13, respectively, by, for example, ultrasonic welding. Contact t2 is welded to the second metal layer 13, respectively, by, for example, ultrasonic welding.

[0093] The first metal layer 12 has an opening 12A. The second metal layer 13 has an opening 13A. When viewed from above in the z direction, the opening 12A is located on the opposite side of the region of the second metal layer 13 connected to the tab t2, across the resin layer 11. At least a portion of the opening 12A overlaps with at least a portion of the tab t2, when viewed from above. The opening 13A is located on the opposite side of the region of the first metal layer 12 connected to the tab t1, across the resin layer 11, when viewed from above. At least a portion of the opening 13A overlaps with at least a portion of the tab t1, when viewed from above. The openings 12A and 13A reach the resin layer 11. The resin layer 11 is exposed at the locations of the openings 12A and 13A.

[0094] Next, a method for manufacturing an electric storage device is described. First, a metal layer is formed on both sides of a commercially available resin film. The metal layer is formed by, for example, sputtering or chemical vapor deposition (CVD).

[0095] Next, the metal layer is removed from the locations opposite to the locations where the tabs t1 and t2 are to be joined. The metal layer can be removed, for example, by photolithography. After a portion of the metal layer is removed, tabs t1 and t2 are joined relative to the removed portions. Tabs t1 and t2 are welded to the metal layer, for example, using ultrasonic welding. Tabs t1 and t2 can be adhered to the metal layer, fixed to the metal layer with screws, or welded to the metal layer by heating, for example. Alternatively, the positive electrode active material layer 20 and the negative electrode active material layer 30 can be stacked, and after removing the positive electrode active material layer 20 and the negative electrode active material layer 30 from the locations where the tabs are to be joined, tabs t1 and t2 can be joined.

[0096] Next, a positive electrode slurry is applied to the surface of one metal layer (the first metal layer 12). The positive electrode slurry is a paste formed by mixing a positive electrode active material, a binder, and a solvent. The positive electrode slurry can be applied using, for example, a die coating method or a doctor blade method.

[0097] The solvent in the applied positive electrode slurry is removed. The removal method is not particularly limited. For example, the current collector 10 coated with the positive electrode slurry is dried in an atmosphere at 80°C to 150°C. The resulting coating is then pressed to increase the density of the positive electrode active material layer 20. The pressing method can be, for example, a roller press or a hydrostatic press.

[0098] Next, the negative electrode slurry is applied to the surface of the metal layer (second metal layer 13) opposite the surface coated with the positive electrode slurry. Negative electrode slurry is a paste formed by mixing a negative electrode active material, a binder, and a solvent. The negative electrode slurry can be applied using the same method as the positive electrode slurry. The solvent in the applied negative electrode slurry can be removed by drying, forming the negative electrode active material layer 30. If the negative electrode active material is metallic lithium, lithium foil can also be attached to the second metal layer 13.

[0099] Next, a separator 40 is placed in contact with the positive electrode active material layer 20 or the negative electrode active material layer 30, and the assembly is wound around one end. The electrode assembly 100 is then enclosed in an outer casing C along with the electrolyte. By encapsulating the assembly while reducing pressure and heating, the electrolyte can penetrate the interior of the electrode assembly 100. When the outer casing C is sealed by heating, etc., the energy storage device 200 is obtained.

[0100] The current collector 10 of the first embodiment has openings 12A and 13A at positions opposite to the positions of the joining tabs t1 and t2, which can suppress short circuits between the first metal layer 12 and the second metal layer 13. When the tabs t1 and t2 are joined, damage is applied to the resin layer 11. For example, cracks may occur in the resin layer 11. When metal layers are present on both sides of the resin layer 11, there is a possibility that the first metal layer 12 and the second metal layer 13 short circuit through the cracks. When the first metal layer 12 and the second metal layer 13 short circuit, the energy storage element 200 does not function properly. However, because the current collector of the first embodiment has openings 12A and 13A at positions opposite to the positions of the joining tabs t1 and t2, short circuits between the first metal layer 12 and the second metal layer 13 can be suppressed even when cracks are present in the resin layer 11. Furthermore, the openings 12A and 13A at positions opposite to the positions where the tabs t1 and t2 are joined can mitigate the local increase in thickness caused by joining the tabs t1 and t2. This can alleviate stress generated by the thickness difference at the joining portion of the tabs t1 and t2.

[0101] For example, the current collector 10 described above has openings 12A and 13A at positions facing tabs t1 and t2, respectively. However, either opening 12A or opening 13A may be provided at a position facing either tab t1 or t2. In this case, the risk of short circuiting is lower than when both openings 12A and 13A are not provided.

[0102] The energy storage element 200 is not limited to an electrode body, but may also be a laminated body. The laminated body is obtained by stacking battery cells in which the separator 40, the negative electrode active material layer 30, the current collector 10, and the positive electrode active material layer 20 are stacked in this order.

[0103] also, Figure 6 This is an enlarged plan view of a characteristic portion of the current collector 10A of the first modification. The shape of the opening 13B of the current collector 10A is similar to that of the Figure 5 The current collector 10 shown is different. In the current collector 10A, Figure 5 The same structures as the current collector 10 shown are denoted by the same reference numerals, and description thereof will be omitted.

[0104] The opening 13B is located on the opposite side of the region of the connection tab t1 of the first metal layer 12 across the resin layer 11 . The opening 13B extends from one end to the other end in the width direction of the second metal layer 13 . The opening 13B reaches the resin layer 11 .

[0105] (Second embodiment)

[0106] The difference between the energy storage device of the second embodiment and the energy storage device 200 of the first embodiment lies in the shape of the current collector.

[0107] Figure 7 This is an enlarged plan view of a characteristic portion of a current collector 50 according to the second embodiment. The current collector 50 includes a resin layer, a first metal layer 52 provided on a first surface of the resin layer, and a second metal layer 53 provided on a second surface of the resin layer.

[0108] The first metal layer 52 includes a first region 52A and a second region 52B. The first region 52A is located opposite the tab-joining portion of the second metal layer 53, where the tab t2 is joined, when viewed from above. At least a portion of the first region 52A overlaps with at least a portion of the tab t2, when viewed from above. The second region 52B is the area of ​​the first metal layer 52 outside the first region 52A. An opening is defined between the first region 52A and the second region 52B, electrically insulating the first region 52A from the second region 52B. Alternatively, an insulator may be embedded in the opening between the first region 52A and the second region 52B.

[0109] The second metal layer 53 includes a third region 53A and a fourth region 53B. The third region 53A is located opposite the tab-joining portion of the first metal layer 52, when viewed from above. At least a portion of the third region 53A overlaps at least a portion of the tab t2, when viewed from above. The fourth region 53B is the area of ​​the second metal layer 53 outside the third region 53A. An opening exists between the third region 53A and the fourth region 53B, electrically insulating the third region 53A from the fourth region 53B. Alternatively, an insulator may be embedded in the opening between the third region 53A and the fourth region 53B.

[0110] The current collector 50 of the second embodiment is configured so that the first region 52A and the second region 52B are insulated, or the third region 53A and the fourth region 54A are insulated. Therefore, even if a short circuit occurs between the first region 52A and the second region 53B, or between the third region 53A and the fourth region 52B, for example, the effect on battery operation is minimal. Therefore, even if cracks occur in the resin layer 11, the effect on the battery element is minimized.

[0111] The same modified examples as those of the energy storage device 200 of the first embodiment can also be applied to the energy storage device of the second embodiment.

[0112] Example

[0113] (Example 1)

[0114] Aluminum with a thickness of 2.1 μm was laminated as the first metal layer on one side of a PET film with a thickness of 6.0 μm. Copper with a thickness of 2.0 μm was laminated as the first metal layer on the side of the PET film opposite to the side laminated with aluminum.

[0115] Next, openings are formed at predetermined locations in the first and second metal layers by photolithography. The openings are similar in shape to the area where the tab to be mounted overlaps the first or second metal layer, but are 10% larger than the area where the tab to be mounted overlaps the first or second metal layer.

[0116] Next, tabs were connected to the first and second metal layers. The tabs were connected at positions corresponding to the respective openings. The potential difference between the first and second metal layers was then measured. The same test was repeated on ten samples. The current collector of Example 1 did not short-circuit in any of the ten samples.

[0117] (Example 2)

[0118] Example 2, as Figure 7 As shown, the first region and the second region are formed in the first metal layer and the second metal layer, respectively, and are insulated from each other, which is different from the first embodiment.

[0119] The dimensions of the first region are the same as the overlapping region of the tab to be mounted and the first or second metal layer. The shape of the opening between the first and second regions is similar to the overlapping region of the tab to be mounted and the first or second metal layer, respectively, but is 10% larger than the overlapping region of the tab to be mounted and the first or second metal layer.

[0120] Next, tabs were connected to the first and second metal layers. The tabs were connected at locations opposite the first region. The potential difference between the first and second metal layers was then measured. The same test was repeated for 10 samples. The current collector of Example 2 did not short-circuit in any of the 10 samples.

[0121] (Comparative Example 1)

[0122] Comparative Example 1 differs from Example 1 in that no opening is provided at a position opposite to the location where the tab is to be attached. The test was conducted under the same conditions as in Example 1. The current collector of Comparative Example 1 short-circuited in 10 out of 10 samples.

[0123] Description of Reference Signs

[0124] 10, 10A, 50 current collector

[0125] 11 Resin layer

[0126] 12, 52 1st metal layer

[0127] 12A, 13A, 13B openings

[0128] 13,53 Second Metal Layer

[0129] 20 Positive electrode active material layer

[0130] 30 Negative electrode active material layer

[0131] 40 diaphragm

[0132] 52A, 53A Area 1

[0133] 52B, 53B Area 2

[0134] 100 Electrode body

[0135] 200 Storage Components

[0136] C outer body

[0137] K Storage Space

[0138] t1, t2 splices.

Claims

1. A current collector, characterized in that: have: a resin layer having a first surface and a second surface facing the opposite side of the first surface; a first metal layer located on the first surface of the resin layer; and a second metal layer located on the second surface of the resin layer, The first metal layer and the second metal layer are insulated by the resin layer, The first metal layer has a first opening for exposing the resin layer. The first opening is located at a position facing a metal plate bonding portion of the second metal layer, and the second metal layer is bonded to a metal plate for electrical connection to the outside at the metal plate bonding portion.

2. The current collector according to claim 1, wherein: The first metal layer has a first region and a second region, The first region is located inside the first opening, and the second region is located outside the first opening. The first region and the second region are separated by the first opening.

3. The current collector according to claim 1 or 2, wherein: The second metal layer has a second opening that exposes the resin layer.

4. The current collector according to claim 3, wherein: The second opening is located at a position facing a metal plate bonding portion of the first metal layer, and the first metal layer is bonded to a metal plate for electrical connection to the outside at the metal plate bonding portion.

5. The current collector according to claim 3 or 4, characterized in that: The second metal layer has a third region and a fourth region, The third region is located inside the second opening, and the fourth region is located outside the second opening. The third region and the fourth region are separated by the second opening.

6. The current collector according to claim 1 or 2, characterized in that: The resin layer is 1.0×10 9 Insulation layer with a thickness of Ω·cm or more.

7. The current collector according to claim 1 or 2, characterized in that: The resin layer includes any one selected from polyethylene terephthalate (PET), polyimide (PI), polyamide-imide (PAI), polypropylene (PP), and polyethylene (PE).

8. The current collector according to claim 1 or 2, wherein: Each of the first metal layer and the second metal layer is any one selected from the group consisting of aluminum, nickel, stainless steel, copper, platinum, and gold.

9. The current collector according to claim 1 or 2, characterized in that: The first metal layer and the second metal layer include different metals.

10. The current collector according to claim 1 or 2, wherein: The first metal layer and the second metal layer include different alloys.

11. An electric storage element, characterized in that: include: The current collector according to any one of claims 1 to 10; a first active material layer formed on the first surface of the current collector; a second active material layer formed on a second surface of the current collector opposite to the first surface; and A separator or a solid electrolyte layer laminated on one side of the first active material layer or the second active material layer.

12. A power storage module, characterized in that: The electric storage device according to claim 11 is included.

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