Current collection structure and power storage device

Abstract

To further improve safety in a bipolar-type power storage device when an internal short circuit occurs.SOLUTION: A current collection structure according to the present disclosure is a current collection structure for a bipolar-type power storage device in which single cells, each having a positive electrode composite layer, a negative electrode composite layer, and an ion conductive medium interposed therebetween, and a current collector are alternately stacked, and the current collector has a lattice-shaped insulating portion and a conductive portion separated into a plurality of polygonal regions by the insulating portion, and two of the current collectors adjacent to each other via the single cell are arranged such that, when viewed transparently in a stacking direction, a portion of one insulating portion overlaps with a portion of the other conductive portion, and a portion of one conductive portion overlaps with a portion of the other insulating portion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This specification discloses a current collecting structure and a power storage device.

Background Art

[0002] Conventionally, a bipolar power storage device in which a single cell including a positive electrode composite layer, a negative electrode composite layer, and an ion conductive medium interposed therebetween, and a current collector are alternately laminated is known. In such a power storage device, a stainless steel foil having a roughened surface is used as the current collector (for example, see Patent Document 1), or a laminated sheet in which conductive layers are formed on the front and back of a resin-containing sheet is used as the current collector (for example, see Patent Document 2), and it has been proposed to improve battery characteristics.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, although Patent Documents 1 and 2 can improve battery characteristics, the safety at the time of internal short circuit occurrence has not been studied. Thus, in a bipolar power storage device, a current collecting structure capable of dealing with internal short circuit has been demanded.

[0005] This disclosure has been made to solve such problems, and an object thereof is to provide a current collecting structure and a power storage device capable of further enhancing the safety at the time of internal short circuit occurrence in a bipolar power storage device.

Means for Solving the Problems

[0006] In order to achieve the above object, as a result of intensive research by the present inventors, a current collector having a lattice-shaped insulating portion and a conductive portion divided into a plurality of polygonal regions by the insulating portion is used. Further, when two adjacent current collectors are viewed through in the stacking direction, a part of one insulating portion and a part of the other conductive portion overlap, and a part of one conductive portion and a part of the other insulating portion overlap, it has been found that the safety at the time of internal short circuit can be further improved, and the invention disclosed in this specification has been completed.

[0007] That is, the current collecting structure disclosed in this specification is a current collecting structure of a bipolar type power storage device in which a single cell including a positive electrode composite layer, a negative electrode composite layer, and an ion conductive medium interposed between the positive electrode composite layer and the negative electrode composite layer, and a current collector are alternately stacked, the current collector has a lattice-shaped insulating portion and a conductive portion divided into a plurality of polygonal regions by the insulating portion, and two adjacent current collectors among the current collectors are, when viewed through in the stacking direction, arranged such that a part of one insulating portion and a part of the other conductive portion overlap, and a part of one conductive portion and a part of the other insulating portion overlap.

[0008] The power storage device disclosed in this specification is a bipolar type power storage device in which a single cell including a positive electrode composite layer, a negative electrode composite layer, and an ion conductive medium interposed between the positive electrode composite layer and the negative electrode composite layer, and a current collector are alternately stacked, the current collector has a lattice-shaped insulating portion and a conductive portion divided into a plurality of polygonal regions by the insulating portion, and two adjacent current collectors among the current collectors are, when viewed through in the stacking direction, arranged such that a part of one insulating portion and a part of the other conductive portion overlap, and a part of one conductive portion and a part of the other insulating portion overlap.

Advantages of the Invention

[0009] The present disclosure can enhance the safety when an internal short circuit occurs in a bipolar power storage device. The reason for obtaining such an effect is presumed as follows. For example, in a bipolar power storage device, when an internal short circuit occurs, since the current concentrates and flows in the surface direction in the current collector from the entire short-circuited electrode toward the short-circuit location, the current may concentrate at the short-circuit location and generate heat. On the other hand, in the present disclosure, a current collector is used in which the conductive part is divided into a plurality of polygonal regions by a lattice-shaped insulating part. Therefore, the energy supplied to the short-circuit location is reduced to the equivalent of the composite electrode on the conductive part separated by the lattice-shaped insulating part, and heat generation is suppressed. Furthermore, in the present disclosure, when two adjacent current collectors are viewed through in the stacking direction, the current collectors are arranged such that a part of one insulating part overlaps with a part of the other conductive part and a part of one conductive part overlaps with a part of the other insulating part. Therefore, the energy supplied to the short-circuit site is reduced to the equivalent of the portion where the composite electrode on the conductive part separated by the lattice-shaped insulating part in one current collector faces the composite electrode on the conductive part separated by the lattice-shaped insulating part in the other current collector, and heat generation is further suppressed. As a result, the safety when an internal short circuit occurs can be further enhanced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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Figure 8

Figure 9

Figure 10

Best Mode for Carrying Out the Invention

[0011] The current collecting structure and the power storage device of the present disclosure described in the embodiments relate to a bipolar power storage device. This power storage device may be, for example, an electric double layer capacitor, a hybrid capacitor, a pseudo electric double layer capacitor, an alkali metal secondary battery, an alkali metal ion battery, or the like. The carrier ions of the power storage device include Group 1 (alkali metal) ions such as lithium ions, sodium ions, and potassium ions, and Group 2 ions such as magnesium ions, strontium ions, and calcium ions. Here, for the sake of convenience of explanation, the case where the power storage device is a lithium ion secondary battery having lithium ions as carriers will be mainly described as an example below.

[0012] The current collecting structure and the power storage device disclosed in this embodiment will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a power storage device 10 which is an example of the power storage device of the present disclosure. FIG. 2 is a cross-sectional view of the power storage device 10 cut in the stacking direction. FIG. 3 is a schematic diagram showing a current collecting structure 12 which is an example of the current collecting structure of the present disclosure, FIG. 3A is a top view, and FIG. 3B is a cross-sectional view of the current collecting structure 12 cut in the stacking direction. However, in FIG. 1, the external current collector 50 on the positive electrode side among the pair of external current collectors 50, the ion conductive medium 36, and the exterior case 60 are omitted. Also, in FIG. 2, the number of stacked current collectors 20 and single cells 30 is reduced compared to FIG. 1.

[0013] As shown in FIGS. 1 and 2, the energy storage device 10 includes an electrode structure 40 in which single cells 30 and current collectors 20 are alternately stacked, and a pair of external current collectors 50. The single cell 30 includes a positive electrode composite layer 32, a negative electrode composite layer 34, and an ion conductive medium 36 interposed between the positive electrode composite layer 32 and the negative electrode composite layer 34. Here, the ion conductive medium 36 is impregnated in a separator 38 interposed between the positive electrode composite layer 32 and the negative electrode composite layer 34. The electrode structure 40 is stacked in multiple stages such that the single cells 30 are in series via the current collector 20 as an internal current collector, that is, the positive electrode composite layer 32 and the negative electrode composite layer 34 are alternately arranged. This electrode structure 40 has a structure in which bipolar electrodes 15 each having a positive electrode composite layer 32 on one surface of the current collector 20 and a negative electrode composite layer 34 on the other surface are stacked. The electrode structure 40 and the external current collector 50 are housed in an exterior case 60.

[0014] The current collector 20 is a sheet-like current collector having a lattice-shaped insulating portion 22 and a conductive portion 21 partitioned by the insulating portion 22 into a plurality of polygonal regions (rectangular regions in this embodiment). The current collector 20 is configured such that the ion conductive medium 36 does not permeate therethrough.

[0015] The material of the conductive portion 21 is not particularly limited, but for example, metals such as copper, nickel, stainless steel, titanium, and aluminum are suitable. Also, the material of the conductive portion 21 may be carbon, fired carbon, a conductive polymer, a conductive glass, an Al-Cd alloy, or the like. Examples of the conductive polymer include polymer materials such as polythiophene-based, polyacetylene-based, polyaniline-based, and polypyrrole-based. Also, the conductive portion 21 may be formed by solidifying an ink in which metal particles or carbon particles as a conductive material are dispersed. Examples of the metal of the conductive material include noble metals such as silver. The conductive portion 21 may have a multilayer structure, for example, a two-layer structure of aluminum and copper. In that case, it is preferable to form the positive electrode composite layer 32 on the aluminum side and the negative electrode composite layer 34 on the copper side. The conductive portion 21 preferably contains aluminum.

[0016] The material of the insulating portion 22 is not particularly limited, but for example, metal oxides such as anodized aluminum are suitable. Also, the material of the insulating portion may be a metal nitride or a metal boride. Further, the material of the insulating portion may be a resin such as epoxy resin (EP), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), etc.

[0017] The current collector 20 may be such that the conductive portion 21 is made of metal and the insulating portion 22 is obtained by making the metal of the conductive portion 21 non-conductive. Such a current collector 20 can be manufactured by a relatively easy process, for example, making a part of a metal, which is a conductor, into an insulator by a non-conductive treatment. For example, the conductive portion 21 may be made of aluminum and the insulating portion 22 may be made of anodized aluminum. Such a current collector can be manufactured by a relatively easy process of making a part of the aluminum, which is a conductor, into anodized aluminum, which is an insulator, by an anodic oxidation treatment. The anodized aluminum insulating portion 22 may have a pore portion, a porous portion, and a barrier layer formed by the anodic oxidation treatment of aluminum. The pore portion is a current-carrying hole formed by the anodic oxidation treatment and opens on the surface of the current collector. The porous portion is a layer of porous alumina and is formed around the pore portion. The barrier layer is a dense layer formed at the bottom of the porous portion. The base aluminum may remain at the bottom of the barrier layer, but it is preferably thin enough to ensure the in-plane insulation of the current collector.

[0018] In the current collector 20, the resistance between adjacent polygonal regions of the conductive portion 21 is preferably 0.5 Ω or more, and may be 1 Ω or more, or may be 5 Ω or more. Note that this resistance may be the resistance due to the lattice of the insulating portion 22.

[0019] The thickness of the current collector 20 is not particularly limited, but from the viewpoint of improving the energy density of the power storage device 10, a thinner thickness is preferable. For example, 100 μm or less is preferable, 50 μm or less is more preferable, and 30 μm or less is even more preferable. From the viewpoint of ensuring the impermeability of the ion conductive medium 36, the thickness of the current collector 20 may be, for example, 5 μm or more, 10 μm or more, or 20 μm or more.

[0020] In the current collector 20, from the viewpoint of increasing the charge-discharge capacity during charge-discharge other than when internal short circuit occurs, the grid width L of the insulating portion 22 is preferably small, for example, preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 2.5 mm or less. From the viewpoints of insulation and ease of manufacturing, this grid width L may be, for example, 0.1 mm or more, may be 0.2 mm or more, or may be 0.5 mm or more. The grid width L of the insulating portion 22 corresponds to the length between adjacent polygonal regions of the conductive portion 21. In the current collector 20, the length X of the polygonal region of the conductive portion 21 separated by the insulating portion 22 is preferably short from the viewpoint of further enhancing the safety when internal short circuit occurs. For example, it is preferably 200 mm or less, may be 150 mm or less, or may be 100 mm or less. From the viewpoint of increasing the charge-discharge capacity during charge-discharge other than when internal short circuit occurs, this length X is preferably large, preferably 10 mm or more, may be 20 mm or more, or may be 40 mm or more. The length X corresponds to the length of one side of the polygonal region separated by the insulating portion 22. The ratio L / X of the length L to the length X may be, for example, 0.01 or more, may be 0.02 or more, or may be 0.05 or more. This ratio L / X may be, for example, 0.3 or less, may be 0.2 or less, or may be 0.1 or less. Note that the length Xp in the parallel direction (the horizontal direction in the figure) parallel to any one side of the polygonal region of the conductive portion 21 and the length Xv in the vertical direction (the vertical direction in the figure) perpendicular to the parallel direction may be the same or different. Similarly, the grid width Lp in the parallel direction and the grid width Lv in the vertical direction of the insulating portion 22 may be the same or different. In the current collector 20, the conductive portion 21 preferably has an area ratio of 80% or more, more preferably 85% or more, and may be 90% or more with respect to the whole of the insulating portion 22. This area ratio is preferably 99% or less, may be 97% or less, or may be 95% or less. This area ratio can enhance the safety more when it is lower, while when it is higher, there are fewer high-resistance regions during charge-discharge other than when internal short circuit occurs, which is preferable. In the current collector 20, the area S of the polygonal region of the conductive portion 21 separated by the insulating portion 22 is preferably small from the viewpoint of further enhancing the safety when internal short circuit occurs. For example, 2 40000 mm or less is preferable, 25000 mm2 It may also be as follows, 10000 mm 2 It may also be as follows. From the viewpoint of increasing the charge-discharge capacity in charge-discharge other than when an internal short circuit occurs, this area S is preferably larger, 100 mm 2 or more is preferable, 400 mm 2 or more may be used, 1600 mm 2 or more may be used. Note that the preferred shapes and dimensions described in this specification relate to the representative conductive part 21 and insulating part 22 arranged in the central part of the current collector 20, and may not apply to the conductive part 21 and insulating part 22 arranged at the peripheral part of the current collector 20.

[0021] Of the current collectors 20, two adjacent ones via the single cell 30 are arranged such that when viewed through in the stacking direction, a part of one insulating part 22 and a part of the other conductive part 21 overlap, and a part of one conductive part 21 and a part of the other insulating part 22 overlap. Hereinafter, regarding such a current collecting structure 12, one of the two current collectors 20 adjacent via the single cell will be described as the first current collector 20a, and the other as the second current collector 20b. The first current collector 20a and the second current collector 20b may be alternately stacked via the single cell 30.

[0022] The first current collector 20a has a lattice-shaped first current collector insulating portion 22a and a first current collector conductive portion 21a partitioned into a plurality of polygonal regions by the first current collector insulating portion 22a. The polygonal regions of the first current collector conductive portion 21a are nine in total, arranged in three rows in the above-mentioned parallel direction and three rows in the above-mentioned vertical direction, and all are squares of the same size. The second current collector 20b has a lattice-shaped second current collector insulating portion 22b and a second current collector conductive portion 21b partitioned into a plurality of polygonal regions by the second current collector insulating portion 22b. The polygonal regions of the second current collector conductive portion 21b are sixteen in total, arranged in four rows in the above-mentioned parallel direction and four rows in the above-mentioned vertical direction. The four arranged in the central portion are squares of the same size as the polygonal regions of the first current collector conductive portion 21a, the four arranged at the four corners are smaller squares than the four arranged in the central portion, and the rest are rectangles with one side having the same length as the side of the square arranged in the central portion and the other side having the same length as the side of the square arranged at the four corners. As shown in FIG. 3, the first current collector 20a and the second current collector 20b are arranged such that the lattice interval Pap of the first current collector 20a and the lattice interval Pbp of the second current collector 20b in the parallel direction are the same, and the lattices are shifted in the parallel direction by 1 / 2 of the lattice interval Pap (=Pbp). Also, the lattice interval Pav of the first current collector 20a and the lattice interval Pbv of the second current collector 20b in the vertical direction are the same, and the lattices are shifted in the vertical direction by 1 / 2 of the lattice interval Pav (=Pbv). Thereby, when viewed in the stacking direction, the polygonal regions of the first current collector conductive portion 21a are quartered by the second current collector insulating portion 22b, and the polygonal regions of the second current collector conductive portion 21b are quartered by the first current collector insulating portion 22a. Also, the area T of the overlapping portion of the first current collector conductive portion 21a and the second current collector conductive portion 21b is equal to or less than 1 / 4 of the area S of the polygonal region of the first current collector conductive portion 21a and equal to or less than 1 / 4 of the area S of the polygonal region of the second current collector conductive portion 21b. Also, the overlapping portion of the first current collector conductive portion 21a and the second current collector conductive portion 21b is 36 locations, and the composite electrode is substantially divided into 36 parts. This number of divisions (the number of overlapping portions of the first current collector conductive portion 21a and the second current collector conductive portion 21b) is not particularly limited, but may be, for example, 30 or more, 50 or more, or 100 or more.This number of divisions may be, for example, 200 or less, or may be 150 or less. The lattice interval is the length of the line segment connecting the midpoints of the lattices on both sides of the portion where the length of the polygonal region is maximized in each direction.

[0023] The positive electrode composite material layer 32 contains a positive electrode active material. The positive electrode composite material layer 32 may be formed, for example, by mixing a positive electrode active material, a conductive material, and a binder, adding an appropriate solvent to form a paste-like positive electrode composite material, applying and drying it in the composite material layer formation region 23 on one surface of the current collector 20, and compressing it as necessary to increase the electrode density. As the positive electrode active material, sulfides containing transition metal elements, oxides containing lithium and transition metal elements, etc. can be used. As the former, transition metal sulfides such as TiS2, TiS3, MoS3, FeS2, etc. can be used, and as the latter, lithium manganese composite oxides, lithium cobalt composite oxides, lithium nickel composite oxides, lithium nickel cobalt manganese composite oxides, lithium vanadium composite oxides, lithium iron phosphate compounds, etc. can be used. As the conductive material, one or a mixture of two or more of graphite such as natural graphite (scaly graphite, flaky graphite) and artificial graphite, acetylene black, carbon black, ketjen black, carbon whiskers, needle coke, carbon fiber, metals (copper, nickel, aluminum, silver, gold, etc.) can be used. As the binder, fluorine-containing resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorine rubber, or thermoplastic resins such as polypropylene and polyethylene, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM rubber, natural butyl rubber (NBR), etc. can be used alone or as a mixture of two or more. As the solvent, organic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N,N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran, etc. can be used.

[0024] The negative electrode composite layer 34 contains a negative electrode active material. For example, the negative electrode composite layer 34 may be formed by mixing a negative electrode active material, a conductive material, and a binder, adding an appropriate solvent to form a paste-like negative electrode composite, applying and drying it in the composite layer formation region 23 on the other surface of the current collector 20, and compressing it as necessary to increase the electrode density. Alternatively, the negative electrode composite layer 34 may be formed by closely adhering the negative electrode active material to the other surface of the current collector 20. As the negative electrode active material, those that can utilize aluminum as the current collector are preferred. For example, the charge-discharge potential is preferably 0.75 V or more, more preferably 0.8 V or more, 1.0 V or more, and 1.2 V or more with respect to the lithium reference potential. Examples of the negative electrode active material include composite oxides, composite materials, and conductive polymers containing a plurality of elements capable of occluding and releasing lithium ions. Examples of the composite oxide include lithium titanium composite oxide and lithium vanadium composite oxide. Examples of the composite material include a layered structure having an organic skeleton layer containing an aromatic compound which is a dicarboxylic acid anion having two or more aromatic ring structures, and an alkali metal element layer in which an alkali metal element coordinates to oxygen contained in the carboxylic acid anion to form a skeleton. Examples of the layered structure include dilithium naphthalenedicarboxylate and dilithium biphenyldicarboxylate. For the conductive material, the binder, and the solvent, the same materials as those used for the positive electrode composite layer 32 can be used.

[0025] The ionic conduction medium 36 may be, for example, a non-aqueous electrolyte containing a supporting salt, a non-aqueous gel electrolyte, or an aqueous electrolyte. Examples of the solvent for the non-aqueous electrolyte include carbonates, esters, ethers, nitriles, furans, sulfolanes, and dioxolanes, and these can be used alone or in combination. Specifically, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate, vinylene carbonate, butylene carbonate, and chloroethylene carbonate; chain carbonates such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate, ethyl-n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate, and t-butyl-i-propyl carbonate; cyclic esters such as γ-butyrolactone and γ-valerolactone; chain esters such as methyl formate, methyl acetate, ethyl acetate, and methyl butyrate; ethers such as dimethoxyethane, ethoxymethoxyethane, and diethoxyethane; nitriles such as acetonitrile and benzonitrile; furans such as tetrahydrofuran and methyltetrahydrofuran; sulfolanes such as sulfolane and tetramethylsulfolane; and dioxolanes such as 1,3-dioxolane and methyldioxolane. Examples of the supporting salt include LiPF6, LiBF4, LiAsF6, LiCF3SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiSbF6, LiSiF6, LiAlF4, LiSCN, LiClO4, LiCl, LiF, LiBr, LiI, and LiAlCl4. The concentration of this supporting salt in the electrolyte is preferably 0.1 mol / L or more and 5 mol / L or less, and more preferably 0.5 mol / L or more and 2 mol / L or less. Further, the ionic conduction medium 36 may be a solid electrolyte.

[0026] The separator 38 insulates the positive electrode composite material layer 32 and the negative electrode composite material layer 34 without inhibiting the ionic conduction of carrier ions. In other words, the separator 38 is configured to allow carrier ions to pass through and not allow electrons to pass through. The separator 38 is not particularly limited as long as it has a composition that can withstand the usage range of the power storage device 10. Examples thereof include polymer nonwoven fabrics such as nonwoven fabrics made of polypropylene and nonwoven fabrics made of polyphenylene sulfide, and thin microporous membranes of olefin resins such as polyethylene and polypropylene. These may be used alone or in combination of a plurality. The thickness of this separator 38 is preferably, for example, 5 μm or more, more preferably 8 μm or more, and may be 10 μm or more. When the thickness is 5 μm or more, it is preferable for ensuring insulation. Further, the thickness of the separator 38 is preferably 15 μm or less, more preferably 10 μm or less. When the thickness is 15 μm or less, it is preferable in terms of suppressing a decrease in ionic conductivity and further reducing the volume occupied in the cell.

[0027] A pair of external current collectors 50 are provided so as to be in contact with the outer electrode composite layers of each of the two single cells 30 located at both ends of the electrode structure 40. The external current collector 50 may have the same structure as the current collector 20 from the viewpoint of enhancing safety when an internal short circuit occurs. Also, the external current collector 50 may have a structure different from that of the current collector 20, for example, it may be composed of a conductor that is a continuous body from the viewpoint of smoothly performing normal charge and discharge. In that case, for the external current collector 50, in addition to, for example, copper, nickel, stainless steel, titanium, aluminum, fired carbon, conductive polymer, conductive glass, Al-Cd alloy, etc., for the purpose of improving adhesion, conductivity, and reduction resistance, for example, those with the surface of copper or the like treated with carbon, nickel, titanium, silver, etc. can also be used. The external current collector 50 may be made of the same material as the current collector 20 or a different material. Examples of the shape of the external current collector 50 include a sheet shape, a net shape, a punched or expanded shape, a lath body, a porous body, a foam body, a formed body of a fiber group, etc. The thickness of the external current collector 50 is preferably the same as or greater than the thickness T of the current collector 20. The thickness of the external current collector 50 may be, for example, 500 μm or less. One side and the other side of the external current collector 50 may have the same material and shape, or at least one of the material and shape may be different.

[0028] The exterior case 60 houses the electrode structure 40 and the external current collectors 50, and has an opening for exposing a part of each external current collector 50. The exterior case 60 is formed, for example, in a cylindrical shape. The material of the exterior case 60 may be, for example, a laminate film, or may be a polymer-metal composite film in which a heat-sealable resin film, a metal foil, and a rigid resin film are laminated in this order from the inside to the outside. As the heat-sealable resin film, for example, polyethylene, ionomer, ethylene vinyl acetate, etc. can be used. As the metal foil, for example, aluminum foil, nickel foil, etc. can be used. As the rigid resin, for example, polyethylene terephthalate, nylon, etc. can be used. The current collector 20 and the external current collectors 50 may be fixed to this exterior case 60 by heat-sealing of the heat-sealable resin film or the like.

[0029] Here, in a bipolar type power storage device, when an internal short circuit occurs, since the current concentrates and flows in the surface direction within the current collector foil from the entire short-circuited electrode toward the short-circuit location, the current concentrates at the short-circuit location and generates heat. For example, the volume resistivity of a general aluminum current collector foil is about 2.5 μΩcm, and the volume resistivity of a general positive electrode composite electrode is about 1 Ωcm. Therefore, the current during a short circuit does not flow in the surface direction of the positive electrode composite electrode, but flows in the surface direction of the current collector foil and concentrates at the short-circuit location, generating heat. The degree of heat generation varies depending on the short-circuit resistance, but sometimes the temperature rises and ignition may occur. However, in the power storage device 10 of the present disclosure, the above-described first current collector 20a and second current collector 20b are used, and a current collection structure 12 is provided such that a part of the first current collector insulating portion 22a and a part of the second current collector conductive portion 21b overlap when viewed through in the stacking direction, and a part of the first current collector conductive portion 21a and a part of the second current collector insulating portion 22b overlap. Therefore, as shown in FIG. 3, the energy supplied to the short-circuit location is reduced to an amount corresponding to the portion where the composite electrode on the first current collector conductive portion 21a separated by the lattice-shaped first current collector insulating portion 22a and the composite electrode on the second current collector conductive portion 21b separated by the lattice-shaped second current collector insulating portion 22b face each other, and heat generation is greatly suppressed. In a bipolar type power storage device, during normal charge and discharge, the charge and discharge current flows in the stacking direction of the stacked electrodes. Therefore, the current flow in the current collector is in the thickness direction. Thus, even if a lattice-shaped insulating portion is provided in the current collector and the resistance of that portion increases, the current does not flow in the plane of the current collector but only in the thickness direction, so charge and discharge are hardly inhibited. For example, the composite electrode on the lattice of the insulating portion has low reactivity and is somewhat difficult to charge and discharge. However, when the width of the lattice of the insulating portion of the current collector is 5 mm, almost charge and discharge occur within 2.5 mm from both ends of the lattice, so charge and discharge performance almost equivalent to that of a current collector without an insulating portion can be obtained. Therefore, in the power storage device 10 of the present disclosure, charge and discharge performance almost equivalent to that obtained when using a current collector without an insulating portion can be obtained. For example, the charge and discharge capacity of the power storage device of the present disclosure can achieve 90% or more or 95% or more of the charge and discharge capacity of a power storage device using a current collector without an insulating portion. Also, since safety can be improved with a relatively small insulating portion, the manufacturing cost of the current collector including the formation cost of the insulating portion can be reduced.

[0030] In the current collector 20 and the power storage device 10 described in detail above, in a bipolar power storage device, the safety during internal short circuit can be further enhanced. The reason for obtaining such an effect is speculated as follows. For example, in a bipolar power storage device, when an internal short circuit occurs, since the current concentrates and flows in the surface direction inside the current collector from the entire short-circuited electrode toward the short-circuit local area, the current may concentrate at the short-circuit location and generate heat. On the other hand, in the current collector 20 of the present disclosure, since it has the current collecting structure 12 described above, the amount of energy supplied to the short-circuit location is reduced. As a result, heat generation can be suppressed and the safety can be further enhanced.

[0031] It should be noted that the present invention is not limited to the above-described embodiments at all, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

[0032] For example, in the above-described embodiment, the polygonal regions of the first current collector 20a and the second current collector 20b are rectangular, but they may be quadrilaterals other than rectangles or polygons other than quadrilaterals. The quadrilateral is preferably, for example, a rectangle such as a square or a rectangle, a parallelogram, or a rhombus. The polygon may be, for example, a hexagon such as a regular hexagon or a triangle such as an equilateral triangle or an isosceles right triangle. FIG. 4 shows a current collection structure 12 as another example, which has a first current collector 20a and a second current collector 20b having a hexagonal polygonal region. FIG. 4A is a top view of the current collection structure 12 of another example, FIG. 4B is a top view of the first current collector 20a of another example, and FIG. 4C is a top view of the second current collector 20b of another example. In FIG. 4, the polygonal regions of the first current collector conductive portion 21a and the second current collector conductive portion 21b are regular hexagons of the same size and are arranged in a honeycomb shape. Among the polygonal regions of the first current collector conductive portion 21a and the second current collector conductive portion 21b, the representative ones arranged in the central portion are regular hexagons, and those arranged in the peripheral portion have a shape with a part of the regular hexagon missing. As shown in FIG. 4, the first current collector 20a and the second current collector 20b are arranged such that the lattice interval Pap of the first current collector 20a and the lattice interval Pbp of the second current collector 20b in the parallel direction are the same, and the lattices are shifted in the parallel direction by 1 / 2 of the lattice interval Pap (= Pbp). Thereby, when viewed through in the stacking direction, the polygonal region of the first current collector conductive portion 21a is trisected by the second current collector insulating portion 22b, and the polygonal region of the second current collector conductive portion 21b is trisected by the first current collector insulating portion 22a. Further, when viewed through in the stacking direction, the area of the overlapping portion of the first current collector conductive portion 21a and the second current collector conductive portion 21b is 1 / 3 or less of the area of the polygonal region of the first current collector conductive portion 21a and 1 / 3 or less of the area of the polygonal region of the second current collector conductive portion 21b.

[0033] In the above-described embodiment, the first current collector 20a and the second current collector 20b are assumed to have polygonal regions with the same shape and dimensions. However, they may have polygonal regions with different shapes and dimensions. Also, they may have similar or congruent shapes and different orientations. The orientation of the polygonal region may be, for example, rotated 30°, 45°, or 60° with respect to one side according to the shape of the polygonal region. Fig. 5 shows a current collecting structure 12 as another example, which has a first current collector 20a and a second current collector 20b having polygonal regions with similar shapes and different orientations. Fig. 5A is a top view of the current collecting structure 12 as another example, Fig. 5B is a top view of the first current collector 20a as another example, and Fig. 5C is a top view of the second current collector 20b as another example. In Fig. 5, the polygonal region of the first current collector conductive portion 21a is arranged in three rows in the parallel direction and three rows in the vertical direction with the same-sized squares, similar to Fig. 3. Also, the polygonal region of the second current collector conductive portion 21b is arranged with a square having a side length approximately √2 times that of the side of the square of the first current collector conductive portion 21a tilted by 45°. Thereby, when viewed in perspective in the stacking direction, the polygonal region of the first current collector conductive portion 21a is bisected by the second current collector insulating portion 22b, and the polygonal region of the second current collector conductive portion 21b is quartered by the first current collector insulating portion 22a. Also, when viewed in perspective in the stacking direction, the area of the overlapping portion of the first current collector conductive portion 21a and the second current collector conductive portion 21b is 1 / 2 or less of the area of the polygonal region of the first current collector conductive portion 21a and 1 / 4 or less of the area of the polygonal region of the second current collector conductive portion 21b. As a result, when viewed in perspective in the stacking direction, there are 18 overlapping portions between the first current collector conductive portion 21a and the second current collector conductive portion 21b, and the composite electrode is substantially divided into 18 parts.

[0034] In the above-described embodiment, the first current collector 20a and the second current collector 20b are assumed to have the same grid width. However, they may have different grid widths.

[0035] In the above-described embodiment, when viewed through in the stacking direction, the polygonal region of the first current collector conductive portion 21a is divided into four equal parts by the second current collector insulating portion 22b, and the polygonal region of the second current collector conductive portion 21b is divided into four equal parts by the first current collector insulating portion 22a. However, it may be divided into three equal parts, two equal parts, or the like. Further, it may not be divided equally. Even when it is not divided equally, when viewed through in the stacking direction, the maximum area of the overlapping portion of the first current collector conductive portion 21a and the second current collector conductive portion 21b is 80% or less (preferably 70% or less, more preferably 50% or less) of the area of the first current collector conductive portion 21a and 80% or less (preferably 70% or less, more preferably 50% or less) of the area of the second current collector conductive portion 21a.

[0036] In the above-described embodiment, the first current collector 20a and the second current collector 20b are such that the lattice is shifted in the parallel direction by 1 / 2 of the lattice pitch in the parallel direction and the lattice is shifted in the vertical direction by 1 / 2 of the lattice pitch in the vertical direction. However, the shift of the lattice may be, for example, 1 / 3, 1 / 4, or the like. Further, the lattice may be shifted only in the parallel direction, only in the vertical direction, or the shift of the lattice in the parallel direction and the shift of the lattice in the vertical direction may be different.

[0037] In the above-described embodiment, the positive electrode active material is the positive electrode active material of a lithium ion secondary battery, but it is not particularly limited. For example, it may be a carbon material used for a capacitor. The carbon material is not particularly limited, and examples thereof include activated carbons, cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, carbon fibers, carbon nanotubes, polyacenes, and the like. Among these, activated carbons showing a high specific surface area are preferable. The activated carbon as the carbon material preferably has a specific surface area of 1000 m 2 / g or more, and more preferably 1500 m 2 / g or more. When the specific surface area is 1000 m 2 / g or more, the discharge capacity can be further increased. The specific surface area of this activated carbon is preferably 3000 m 2 / g or less, and preferably 2000 m 2It is more preferably below / g. In the positive electrode, it is considered that at least one of the anions and cations contained in the ion conductive medium is adsorbed and desorbed for power storage. Furthermore, it may be one that inserts and desorbs at least one of the anions and cations contained in the ion conductive medium for power storage.

[0038] This disclosure may also be as shown in any one of the following [1] to

[10] . [1] A bipolar type power storage device having a single cell including a positive electrode composite layer, a negative electrode composite layer, and an ion conductive medium interposed between the positive electrode composite layer and the negative electrode composite layer, and a current collector, and a current collection structure in which the current collectors are alternately laminated, wherein the current collector has a lattice-shaped insulating portion and a conductive portion partitioned into a plurality of polygonal regions by the insulating portion, and among the current collectors, two adjacent ones through the single cell are arranged such that when viewed through in the stacking direction, a part of one insulating portion and a part of the other conductive portion overlap, and a part of one conductive portion and a part of the other insulating portion overlap. [2] The current collection structure according to [1], wherein among the current collectors, two adjacent ones through the single cell are arranged such that when viewed through in the stacking direction, the maximum area of the overlapping part of one conductive portion and the other conductive portion is 80% or less of the area of one polygonal region and 80% or less of the area of the other polygonal region. [3] The current collection structure according to [1] or [2], wherein the polygonal region is a quadrilateral or a hexagon. [4] The current collection structure according to any one of [1] to [3], wherein among the current collectors, two adjacent ones through the single cell are arranged such that when viewed through in the stacking direction, at least one of the following conditions is satisfied: the lattice interval in the parallel direction parallel to any side of the polygonal region is the same and the lattice is shifted in the parallel direction, or the lattice interval in the vertical direction perpendicular to the parallel direction is the same and the lattice is shifted in the vertical direction. [5] Among the current collectors, two adjacent ones via the single cell are arranged such that when viewed through in the stacking direction, at least one of the following conditions is satisfied: the lattice spacing in the parallel direction is the same and the lattice is shifted in the parallel direction by 1 / 2 of the lattice spacing in the parallel direction, or the lattice spacing in the vertical direction is the same and the lattice is shifted in the vertical direction by 1 / 2 of the lattice spacing in the vertical direction. The current collector structure according to [4]. [6] Among the current collectors, two adjacent ones via the single cell are arranged such that when viewed through in the stacking direction, the shapes of the polygonal regions are similar or congruent and the orientations are different. The current collector structure according to any one of [1] to [5]. [7] The lattice width of the insulating portion is 2.5 mm or less. The current collector structure according to any one of [1] to [6]. [8] The conductive portion contains aluminum. The current collector structure according to any one of [1] to [7]. [9] A bipolar type power storage device in which a single cell including a positive electrode composite layer, a negative electrode composite layer, and an ion conductive medium interposed between the positive electrode composite layer and the negative electrode composite layer, and a current collector are alternately stacked. The current collector has a lattice-shaped insulating portion and a conductive portion partitioned into a plurality of polygonal regions by the insulating portion. Among the current collectors, two adjacent ones via the single cell are arranged such that when viewed through in the stacking direction, a part of one insulating portion and a part of the other conductive portion overlap, and a part of one conductive portion and a part of the other insulating portion overlap. A power storage device.

Example

[0039] Hereinafter, examples of examining the above-described power storage device will be described as experimental examples. Note that Experimental Example 3 corresponds to an example of the present disclosure, and Experimental Example 1 corresponds to a comparative example. Experimental Example 2 corresponds to a reference example.

[0040] In the experimental examples, a bipolar battery with a composite electrode (composite layer formation region) having an area of 500 mm × 500 mm, a capacity of 5 Ah, a stacking number of single cells of 3 layers (the stacking number of current collectors is a total of 4 layers including 2 layers of internal current collectors and 2 layers of external current collectors), and a battery voltage of 12 V (4 V × 3 in series) was examined.

[0041] (Experimental Example 1) A bipolar battery having the current collecting structure 112 of FIG. 6 was studied. FIG. 6A is a top view of the current collecting structure 112, and FIG. 6B is a cross-sectional view of the current collecting structure 112 cut in the stacking direction. The first current collector 120a was configured with a first current collector conductive part 121a which is a metal current collecting foil. The second current collector 120b was configured with a second current collector conductive part 121b which is a metal current collecting foil. In Experimental Example 1, when an internal short circuit occurs, 20Wh of energy equivalent to a voltage of 4V with a capacity of 5Ah is concentrated at the short circuit location from the entire composite electrode of 500mm x 500mm. Therefore, it was presumed that when a short circuit occurs with low resistance, 20Wh is supplied to the short circuit local area in a short time, and heat generation is relatively likely to increase.

[0042] (Experimental Example 2) The bipolar battery having the current collecting structure 212 of FIG. 7 was studied. FIG. 7A is a top view of the current collecting structure 2212, and FIG. 7B is a cross-sectional view of the current collecting structure 212 cut in the stacking direction. The first current collector 220a is assumed to have a lattice-shaped first current collector insulating portion 222a and a first current collector conductive portion 221a which is a metal current collector partitioned into a plurality of polygonal regions (here, 6×6 = 36 square regions) by the first current collector insulating portion 222a. The second current collector 220b is assumed to have a lattice-shaped second current collector insulating portion 222b and a second current collector conductive portion 221b which is a metal current collector partitioned into a plurality of polygonal regions (here, 6×6 = 36 square regions) by the second current collector insulating portion 222b. The first current collector 220a and the second current collector 220b are such that when viewed through in the stacking direction, the first current collector conductive portion 221a and the second current collector conductive portion 221b overlap, and the first current collector insulating portion 222a and the second current collector insulating portion 222b overlap. In Experimental Example 2, since the composite electrode is substantially divided into 36 parts due to the presence of the lattices (insulating portions 222a, 222b), when an internal short circuit occurs, only 0.556 Wh of energy corresponding to a capacity of 0.139 Ah (5 Ah / 36) is supplied to the short-circuited portion. Therefore, it was inferred that the amount of heat generation when an internal short circuit occurs can be suppressed. In Experimental Example 2, there was a problem that the length of the lattices required to divide the composite electrode into 36 parts reached about 14 m (500 mm×14×2) for both the positive and negative electrodes and the cost of the lattice-shaped current collecting foil became high.

[0043] Incidentally, since the positive electrode composite layer and the negative electrode composite layer disposed on the insulating lattice become less likely to react as the width of the insulating lattice increases, there is a concern that the charge-discharge capacity decreases as the width of the insulating lattice increases. Therefore, regarding the bipolar battery of Experimental Example 2, a simulation model was used to change the lattice width of the insulating portion and the area of the polygonal region of the conductive portion, and the capacity retention rate with respect to the entire surface current collection using a metal foil was obtained. In this simulation model, the metal foil is a clad material of Al and Cu, and it was assumed that a positive electrode composite layer is formed on the Al side and a negative electrode composite layer is formed on the Cu side.

[0044] First, as calculation model 1, the capacity retention rate was examined when lattice-shaped insulating parts were installed for both Al for positive electrode current collection and Cu for negative electrode current collection. Specifically, the capacity Q [Ah] was derived when the area of the polygonal region and the lattice width were changed, and the capacity retention rate Qratio [-] (Qratio = Q / Qall), which is the ratio of the capacity Q to the capacity Qall [Ah] when the entire current collector is a metal current collecting foil, was derived. The examination results of calculation model 1 are shown in Fig. 8. Note that Fig. 8A is an explanatory diagram of calculation model 1, Fig. 8B is a graph showing the relationship between the lattice width and the capacity retention rate during 4C discharge, and Fig. 8C is a graph showing the relationship between the lattice width and the capacity retention rate during 4C charge. From Fig. 8, it was found that the larger the area of the polygonal region, the more the capacity can be maintained even when the lattice width is widened. Also, since the capacity retention rate is lower during charging, it was found that the lattice width is preferably determined by the target charging capacity. When the target capacity retention rate is set to 0.95, when the area of the polygonal region is 1600 mm 2 (40 mm × 40 mm), it can be achieved with a lattice width of 2 mm or less, and when the area of the polygonal region is 6400 mm 2 (80 mm × 80 mm), it was found that it can be achieved with a lattice width of 2.5 mm or less. However, by increasing the area of the polygonal region, the influence of the decrease in the electrochemical reaction at the insulated lattice width can be relatively reduced, but since the influence itself does not disappear, it can be read from Fig. 8 that the lattice width cannot be widened without limit. Also, the larger the area of the polygonal region, the more the amount of energy concentrated at the time of internal short circuit occurrence, and the more the heat generation amount. Therefore, from the viewpoint of suppressing the heat generation amount, it was inferred that the lattice width is preferably 3 mm or less.

[0045] Next, as the calculation model 2, the capacity retention rate when a lattice-shaped insulating part was installed only on the Al for the positive electrode current collector was examined. The examination results of the calculation model 2 are shown in Fig. 9. Note that Fig. 9A is an explanatory diagram of the calculation model 2, Fig. 9B is a graph showing the relationship between the width of the lattice (the gap between the positive electrode current collector Als) and the capacity retention rate during 4C discharge, and Fig. 9C is a graph showing the relationship between the width of the lattice (the gap between the positive electrode current collector Als) and the capacity retention rate during 4C charge. Comparing Fig. 9B with Fig. 8B, the relationship between the lattice width and the discharge capacity retention rate showed almost the same tendency. Also, comparing Fig. 9C with Fig. 8C, the relationship between the lattice width and the charge capacity retention rate showed almost the same tendency. From these facts, it was inferred that most of the influence of the insulating lattice originated from the lattice on the Al side. Also, it was inferred that if the lattice width was set assuming the case where insulating parts were installed on both the Al and Cu sides, the target capacity could be achieved even if the lattice was arranged only on the Al side.

[0046] Furthermore, as the calculation model 3, the capacity retention rate when a lattice-shaped insulating part was installed only on the Cu for the negative electrode current collector was examined. The examination results of the calculation model 3 are shown in Fig. 10. Note that Fig. 10A is an explanatory diagram of the calculation model 3, Fig. 10B is a graph showing the relationship between the width of the lattice (the gap between the negative electrode current collector Cus) and the capacity retention rate during 4C discharge, and Fig. 10C is a graph showing the relationship between the width of the lattice (the gap between the negative electrode current collector Cus) and the capacity retention rate during 4C charge. From Fig. 10B, it was found that the lattice width on the Cu side had almost no influence on the discharge capacity retention rate. From Fig. 10C, as the lattice width on the Cu side increased, the charge capacity retention rate decreased slightly, but the decrease in the capacity retention rate was less than that in Fig. 8C. Therefore, it was inferred that if the lattice width was set assuming the case where insulating parts were installed on both the Al and Cu sides, the target capacity could be achieved even if the lattice was arranged only on the Cu side.

[0047] (Experimental Example 3) A bipolar battery having the current collecting structure 12 of Fig. 3 was examined. The first current collector 20a had a lattice-shaped first current collector insulating part 22a and a first current collector conductive part 21a, which is a metal current collector divided into a plurality of polygonal regions (here, nine square regions) by the first current collector insulating part 22a. The second current collector 20b had a lattice-shaped second current collector insulating part 222b and a second current collector conductive part 221b, which is a metal current collector divided into a plurality of polygonal regions (here, 16 rectangular regions, represented by four square regions), by the second current collector insulating part 222b. This second current collector 20b has a structure in which the lattice of the first current collector 20a is shifted by 1 / 2 of the lattice period vertically and horizontally. As a result, when first current collector 20a and second current collector 20b are seen through in the stacking direction, a part of first current collector insulating portion 22a overlaps a part of second current collector conductive portion 21b, and a part of first current collector conductive portion 21a overlaps a part of second current collector insulating portion 22b. In experimental example 3, the presence of the lattice (insulating portions 22a, 22b) effectively divides the composite electrode into 36 portions, and it is presumed that, as in experimental example 2, the amount of heat generated when an internal short circuit occurs can be suppressed. In addition, in Experimental Example 3, insulating portion 22a of first current collector 20a divides conductive portion 21a into 9 square regions, and insulating portion 22b of second current collector 20b only divides conductive portion 21a into 16 rectangular regions, so that the length of the grid required to divide the composite electrode into 36 portions can be reduced to approximately 9 m (500 mm × (8 pieces + 10 pieces)) for the positive and negative electrodes combined, which is presumed to be preferable from the viewpoint of cost reduction. Note that, from the results of the study of calculation models 1 to 3 in Experimental Example 2, it was presumed that the target capacity retention rate can be achieved even if there is a region where the grid is installed only on one side as in Experimental Example 3, if the grid width is set so that the target capacity retention rate can be achieved assuming that the grid is installed on both sides of the current collecting metal.

[0048] Note that it is also conceivable to use only the first current collector 20a as the current collector 20. Even in this case, due to the presence of the lattice (insulating portion 22a), the composite electrode is substantially divided into nine parts, and the amount of heat generated when an internal short circuit occurs can be suppressed to some extent. However, by using the first current collector 20a and the second current collector 20b, the substantial number of divisions of the composite electrode can be significantly increased, and the amount of heat generated when an internal short circuit occurs can be further suppressed. Therefore, the structure of Experimental Example 3 is more preferable.

[0049] From the above, it has been found that by using a current collector having a lattice-shaped insulating portion and a conductive portion divided into a plurality of polygonal regions by the insulating portion, the safety when an internal short circuit occurs can be enhanced. Further, when two adjacent current collectors are viewed through in the stacking direction, by making a part of one insulating portion overlap with a part of the other conductive portion and a part of one conductive portion overlap with a part of the other insulating portion, it has been found that the safety when an internal short circuit occurs can be further enhanced.

[0050] Note that the present disclosure is not limited to the above-described embodiments at all, and it goes without saying that the present disclosure can be implemented in various modes as long as it belongs to the technical scope of the present disclosure.

Industrial Applicability

[0051] The present disclosure can be applied to the technical field of power storage devices.

Explanation of Reference Numerals

[0052] 10 Energy storage device, 12 Current collector structure, 15 Bipolar electrode, 20 Current collector, 20a First current collector, 20b Second current collector, 21a First current collector conductive part, 21b Second current collector conductive part, 22a First current collector insulating part, 22b Second current collector insulating part, 23 Composite material layer formation region, 30 Single cell, 32 Positive electrode composite material layer, 34 Negative electrode composite material layer, 36 Ion conductive medium, 38 Separator, 40 Electrode structure, 50 External current collector, 60 Exterior case, 112 Current collector structure, 120a First current collector, 120b Second current collector, 121a First current collector conductive part, 121b Second current collector conductive part, 212 Current collector structure, 220a First current collector, 220b Second current collector, 221a First current collector conductive part, 221b Second current collector conductive part, 222a First current collector insulating part, 222b Second current collector insulating part.

Claims

1. A current collecting structure of a bipolar type power storage device in which a single cell including a positive electrode composite material layer, a negative electrode composite material layer, and an ion conductive medium interposed between the positive electrode composite material layer and the negative electrode composite material layer, and a current collector are alternately laminated, wherein the current collector has a lattice-shaped insulating portion and a conductive portion partitioned into a plurality of polygonal regions by the insulating portion, and when two adjacent current collectors among the current collectors are viewed through the single cell in the stacking direction, a part of one insulating portion and a part of the other conductive portion overlap, and a part of one conductive portion and a part of the other insulating portion overlap. Current collecting structure.

2. When two adjacent current collectors among the current collectors are viewed through the single cell in the stacking direction, the maximum area of the overlapping portion of one conductive portion and the other conductive portion is 80% or less of the area of one polygonal region and 80% or less of the area of the other polygonal region. The current collecting structure according to claim 1.

3. The polygonal region is a quadrilateral or a hexagon. The current collecting structure according to claim 1 or 2.

4. When two adjacent current collectors among the current collectors are viewed through the single cell in the stacking direction, at least one of the following conditions is satisfied: the lattice interval in the parallel direction parallel to any side of the polygonal region is the same and the lattice is shifted in the parallel direction, or the lattice interval in the perpendicular direction perpendicular to the parallel direction is the same and the lattice is shifted in the perpendicular direction. The current collecting structure according to claim 1 or 2.

5. When two adjacent current collectors among the current collectors are viewed through the single cell in the stacking direction, at least one of the following conditions is satisfied: the lattice interval in the parallel direction is the same and the lattice is shifted by 1 / 2 of the lattice interval in the parallel direction in the parallel direction, or the lattice interval in the perpendicular direction is the same and the lattice is shifted by 1 / 2 of the lattice interval in the perpendicular direction in the perpendicular direction. The current collecting structure according to claim 4.

6. When two adjacent current collectors among the current collectors are viewed through the single cell in the stacking direction, the shapes of the polygonal regions are similar or congruent and are arranged so as to have different orientations. The current collecting structure according to claim 1 or 2.

7. The lattice width of the insulating portion is 2.5 mm or less. The current collecting structure according to claim 1 or 2.

8. The conductive portion contains aluminum. The current collecting structure according to claim 1 or 2.

9. A bipolar type power storage device in which a single cell including a positive electrode composite layer, a negative electrode composite layer, and an ion conductive medium interposed between the positive electrode composite layer and the negative electrode composite layer, and a current collector are alternately laminated, wherein the current collector has a lattice-shaped insulating portion and a conductive portion partitioned into a plurality of polygonal regions by the insulating portion, and two adjacent ones of the current collectors via the single cell, when viewed through in the stacking direction, are arranged such that a part of one insulating portion and a part of the other conductive portion overlap, and a part of one conductive portion and a part of the other insulating portion overlap, Power storage device.

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