JP2023065025A - Structure, power storge device and method for manufacturing power storage device - Google Patents

Abstract

To simplify the manufacturing process as much as possible.SOLUTION: The structure of the present disclosure is a structure used in a power storage device, comprises a separator, a positive electrode collector formed on the first surface of the separator and having an opening that is connected to the separator, and a negative electrode collector formed on the second surface of the separator and having an opening that is connected to the separator.SELECTED DRAWING: Figure 1

Description

Disclosed herein are structures, electrical storage devices, and methods of manufacturing electrical storage devices.

Conventionally, as an electricity storage device, an electrode active material, a plurality of collecting lines which are not electrically connected to each other at a portion adjacent to the electrode active material and in contact with the electrode active material, and the collecting line and the electrode active material. It has been proposed to provide an electricity storage device electrode having a comb tooth structure current collector having a current collector that is a continuous body that connects a plurality of collecting wires in parallel outside that are not in contact (for example, patent Reference 1). In this electricity storage device, the sheet-like electrode can develop a slow discharge mechanism during an internal short circuit.

Japanese Patent Application Laid-Open No. 2021-144800

By the way, when manufacturing an electric storage device, there are many steps such as applying an electrode mixture onto a current collector and laminating the device with a separator, and it has been demanded to simplify the manufacturing process as much as possible. In Patent Literature 1 described above, although the sheet-like electrode can develop a slow discharge mechanism at the time of an internal short circuit, simplification of the manufacturing method as much as possible has not been considered.

The present disclosure has been made in view of such problems, and a main object thereof is to provide a structure, an electricity storage device, and a method for manufacturing an electricity storage device that can simplify the manufacturing process as much as possible.

As a result of intensive research to achieve the above-described object, the present inventors have found that the manufacturing process of an electricity storage device having sheet-like electrodes can be simplified by forming current collectors having openings on the front and back of a separator. The present inventors have found that it is possible to achieve this, and have completed the invention disclosed in this specification.

That is, the structures disclosed herein are
A structure used in an electricity storage device,
a separator;
a positive electrode current collector having an opening formed on the first surface of the separator and communicating with the separator;
a negative electrode current collector having an opening formed on the second surface of the separator and communicating with the separator;
is provided.

The electricity storage device disclosed herein is
a structure as described above;
a positive electrode mixture layer formed on the side of the positive electrode current collector;
a negative electrode mixture layer formed on the negative electrode current collecting portion side;
is provided.

The method for manufacturing an electricity storage device disclosed herein includes:
A method for manufacturing an electricity storage device,
a separator, a positive current collector having an opening formed on a first surface of the separator and communicating with the separator, and a negative current collector having an opening formed on a second surface of the separator and communicating with the separator. A positive electrode structure manufacturing step of forming a positive electrode mixture layer on the positive electrode current collector side of the structure provided with a positive electrode structure to obtain a positive electrode structure;
a negative electrode structure producing step of forming a negative electrode mixture layer on the negative electrode current collector side of the structure to obtain a negative electrode structure;
A stacking step of stacking the positive electrode structure and the negative electrode structure;
includes.

The present disclosure can simplify the manufacturing process as much as possible. The reason why such an effect is obtained is presumed as follows. For example, a conventional electricity storage device such as a lithium battery composed of sheet-like electrodes requires three types of separators, a positive electrode current collector foil, and a negative electrode current collector foil. Since there is only one type of structure, which is a separator with an electric body formed thereon, it is easy to handle. In the conventional structure, the positive electrode mixture is applied to the surface of the positive electrode current collector, and then the positive electrode mixture is applied again to the back surface of the positive electrode current collector. is applied, and then the negative electrode mixture is applied again to the back surface of the negative electrode current collector to obtain positive/negative electrodes. Therefore, in the conventional sheet-like electrode, it is necessary to apply the composite material four times. Since the negative electrode mixture is applied to the electric body side and these are laminated, the application of the mixture is only required twice. In addition, in the conventional sheet-like electrode, three steps of laminating a separator on a positive electrode current collector formed with a positive electrode mixture and further laminating a negative electrode current collector formed with a negative electrode mixture are required. In the present disclosure, only two steps of laminating the structure having the negative electrode composite material on the structure having the positive electrode composite material formed thereon are required. In addition, in the conventional structure, since the metal current collector is in the form of a foil, the electrolytic solution permeation path to the electrode after lamination is only in the surface direction, and it takes time to inject the electrolytic solution. Since the positive and negative electrode current collectors have openings that communicate with the separator, the electrolyte permeates the current collector not only in the surface direction but also in the thickness direction, so that the permeation of the electrolyte can be performed more smoothly. In addition, in the present disclosure, the current collector of the positive and negative electrodes has an opening, and the proportion of the current collector in the laminated electrode is reduced, so that the proportion of the positive and negative electrode active materials is relatively increased, and the energy Density can be improved. Thus, the structure of the present disclosure can simplify the manufacturing process as much as possible.

1 is a schematic diagram showing an example of a structure 10; FIG. FIG. 2 is a schematic diagram showing an example of an electricity storage device 20; The schematic diagram which shows an example of another structure 10B. The schematic diagram which shows an example of another electrical storage device 20B. Explanatory drawing of the number of components of an Example and a comparative example. Explanatory drawing of the number of times of coating in an example and a comparative example. Explanatory drawing of the number of times of lamination in the example and the comparative example. Explanatory drawing which impregnates with the electrolyte solution of an Example and a comparative example. Explanatory drawing at the time of partial short circuit of an Example.

(Structure)
A structure of the present disclosure described in an embodiment is used for an electricity storage device. The structure includes a separator, a positive current collector, and a negative current collector. The separator is a member that has insulating properties and can impart ionic conductivity. The positive electrode current collector is a conductive member formed on the first surface of the separator and having an opening communicating with the separator. The negative electrode current collector is a conductive member formed on the second surface of the separator and having an opening communicating with the separator.

A structure and a power storage device disclosed in this embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the structure 10. As shown in FIG. FIG. 2 is a schematic diagram showing an example of the electricity storage device 20. As shown in FIG. FIG. 3 is a schematic diagram showing an example of another structure 10B. FIG. 4 is a schematic diagram showing an example of another power storage device 20B. The structure 10 has a structure in which a positive electrode current collector 14 and a negative electrode current collector 17 are arranged at positions facing each other with a separator 13 interposed therebetween. Further, the structural body 10B has a structure in which the positive electrode current collector 14 and the negative electrode current collector 17 are arranged at offset positions with the separator 13 interposed therebetween. As shown in FIG. 1 , the structure 10 has a positive electrode current collector 14 formed on the first surface 11 of the separator 13 and a negative electrode current collector 17 formed on the second surface 12 opposite to the first surface 11 . ing.

The separator 13 insulates the positive electrode 25 and the negative electrode 26 without impeding ion conduction of carrier ions (for example, lithium ions). The separator 13 is not particularly limited as long as it has a composition that can withstand the range of use of the structure 10. Examples of the separator 13 include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyvinylidene fluoride, Vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-fluoroethylene Copolymer, vinylidene fluoride-hexafluoroacetone copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-propylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-tetrafluoro Fluorinated resins such as ethylene-hexafluoropropylene copolymer and vinylidene fluoride-ethylene-tetrafluoroethylene copolymer, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, poly Polyethers such as ethylene oxide and polypropylene oxide, celluloses such as carboxymethyl cellulose and hydroxypropyl cellulose, polymer compounds and their derivatives mainly composed of poly(meth)acrylic acid and other esters, copolymers and mixtures thereof A film made of Moreover, these may be used independently and may be used in combination. In addition, these films may be added with various additives such as additives for enhancing ionic conductivity and for enhancing strength and corrosion resistance. Among these microporous films, polyethylene, polypropylene, polyvinylidene fluoride, polysulfone and the like are preferably used. The separator is preferably microporous so that the non-aqueous electrolyte can permeate and the ions can easily pass through. The thickness of the separator 13 is, for example, preferably 5 μm or more, more preferably 8 μm or more, and may be 10 μm or more. A thickness of 5 μm or more is preferable for ensuring insulation. The thickness of the separator 13 is preferably 20 μm or less, more preferably 15 μm or less, and may be 10 μm or less. A thickness of 20 μm or less is preferable in terms of suppressing a decrease in ionic conductivity and further reducing the volume occupied in the cell.

Separator 13 may be a solid electrolyte as an ion-conducting medium. Examples of solid electrolytes include inorganic solid electrolytes and polymer solid electrolytes. The solid electrolyte is not limited to the following composition and structure, and any material to which Li ions can move may be used. As long as the compounds exemplified below are used as the basic skeleton, they can be used even if they are partially substituted or have different composition ratios. Examples of inorganic solid electrolytes include Li ₃ N, Li ₁₄ Zn(GeO ₄ ) ₄ called LISICON, sulfide Li _3.25 Ge _0.25 P _0.75 S ₄ , perovskite La _0.5 Li _0.5 TiO ₃ , (La _{2/ 3Li3x □ 1 /3-2x ) TiO3} (□: _atomic vacancies) _, garnet-type _Li7La3Zr2O12 , NASICON-type _{LiTi2 ( PO4} ) ₃ , _{Li1.3M0.3Ti1.7} (PO ₃ ) ₄ (M=Sc, Al), Li ₇ P ₃ S ₁₁ obtained from a glass ceramic with a composition of 80Li ₂ S.20P ₂ S ₅ (mol %), and a sulfide system with high electrical conductivity. Li ₁₀ Ge _{2 PS 2 , which} is _a substance _{having a high coefficient of -SiS2 - Li4SiO4 , Li2SP2S5 , Li3PO4 - Li4SiO4} , _{Li3BO4 - Li4SiO4 ,} and _{SiO2 , GeO2} , _{B2O3 ,} Examples include those using P ₂ O ₅ as a glass material and Li ₂ O as a network modifier, and thiolysicone solid electrolytes such as Li ₂ S—GeS ₂ system, Li ₂ S—GeS ₂ --ZnS system, Li ₂ S— Ga ₂ S ₂ system, Li ₂ S--GeS ₂ --Ga ₂ S ₃ system, Li ₂ S--GeS ₂ --P ₂ S ₅ system, Li ₂ S--GeS ₂ --SbS ₅ system, Li ₂ S--GeS ₂ -- Al ₂ S ₃ system, Li ₂ S--SiS ₂ system, Li ₂ SP ₂ S ₅ system, Li ₂ S--Al ₂ S ₃ system, LiS--SiS ₂ --Al ₂ S ₃ system, Li ₂ S--SiS ₂ -P ₂ S ₅ system and the like.

Polymer solid electrolytes include, for example, a complex of polyethylene oxide (PEO) and an alkali metal. Polymers are not limited to PEO, but examples of unit structures of polymer materials that dissolve lithium salts include polyether systems. PEO, PPO: poly(propylene oxide), Polyamine-based PEI: poly(ethylene imine), PAN: poly(acrylo nitrile), Polysulfide-based PAS: poly(ethylene sulfide), and the like. Lithium _salts include LiTFSI _: (LiN( _SO2CF3 ) _{2 ) , LiPEI} : ( _COCF2SO2NLi )n, and LiPPI: (COCF( _{CF3OCF2CF2SO2NLi} )) _n . Gel polymer electrolytes using PVdF (PolyVinylidene DiFluoride), PAN, HFP (Hexafluoropropylene) and the like are also included. Organic ionic plastic electrolytes include those having a plastic crystal phase. Representative molecules of the plastic crystal phase include Tetrachloromethane, Cyclohexane, Succinonitrile, etc., and _Tf2N : (trifluoromethylsulfonyl)amide, _LiBF4 are added to these plastic crystal phases, or aliphatic quaternary ammonium and a salt having a plastic crystal phase consisting of a perfluoroanion. Organic-inorganic hybrid ion gels that mix ionic liquids and glass components at the molecular level, namely, organic boron-based ion gel electrolytes using cellulose, organic boron-based ion gel electrolytes using amylose, boron multi-substituted macrocycles derived from cyclodextrin etc.

The positive electrode current collector 14 is a member having a comb-teeth structure including a collecting wire 14a, a connection portion 15, and an opening portion 16. As shown in FIG. The collecting line 14a is a plurality of linear members that are not electrically connected to each other at the portions that are adjacent to the positive electrode active material and are in contact with the positive electrode active material. The collector line 14a may have a square or rectangular cross-sectional shape, or a polygonal column such as a cylindrical column, an elliptical column, a hexagonal column, or an octagonal column. The connecting part 15 is a member that is a continuous body that connects the plurality of collecting wires 14a in parallel outside where the collecting wires 14a and the positive electrode active material are not in contact with each other. The connecting portion 15 is a foil-like or plate-like member whose longitudinal direction is the arrangement direction of the collecting lines 14a. The opening 16 is a space that communicates with the separator 13 and is formed between the collecting lines 14a. The positive electrode current collector 14 has a plurality of openings 16 . The opening 16 is filled with the positive electrode mixture layer 21 .

In addition to copper, nickel, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al—Cd alloy, etc., the collecting line 14a is made of materials such as For example, copper or the like whose surface has been treated with carbon, nickel, titanium, silver, or the like can also be used. For these, it is also possible to oxidize the surface. It is preferable that the width t of the collecting line 14a is in the range of 100 μm to 500 μm, and the width s of the opening 16 is in the range of 100 μm to 500 μm. The width t and the width s may be the same value or different values, but considering the support during lamination, the same value is preferable. The width t of the collecting line 14a is more preferably 200 μm or more, and may be 250 μm or more. Further, the width t of the collecting line 14a is more preferably 400 μm or less, and may be 300 μm or less. The width s of the opening 16 is more preferably 200 μm or more, and may be 250 μm or more. Further, the width s of the opening 16 is more preferably 400 μm or less, and may be 300 μm or less. The length L of the collecting line 14a may be appropriately selected according to the characteristics required for the power storage device 20, and may be, for example, 5 cm or more, or 10 cm or more and 20 cm or more. Also, the length of the opening 16 may be the same as the length L of the collecting line 14a.

The connecting portion 15 may be configured such that the collecting lines 14a having a number M of 100 or more are connected in parallel, or the collecting lines 14a having a number M of 200 or more or 500 or more may be connected in parallel. . Since the resistance applied to the single cell 23 via the connection portion 15 is determined according to the number M of parallel connections, the number M of parallel connections of the collecting lines 14a, the connection portions 15 and The volume resistivity of the collecting line 14a may be appropriately set. Moreover, since the amount of the negative electrode active material per unit volume decreases as the number M of the collecting lines 14a increases, the number M of the collecting lines 14a may be appropriately set in consideration of the energy density. The positive electrode current collector 14 may have a volume resistivity of 1.0×10 ⁻⁷ Ωm or less. Further, the positive electrode current collector 14 may have a volume resistivity of 5.0×10 ⁻⁸ Ωm or less, or may have a volume resistivity of 2.0×10 ⁻⁸ Ωm or less. The volume resistivity of the collecting line 14a and the connection portion 15 may be the same or different.

The negative electrode current collector 17 is a member having a comb-teeth structure including a collecting wire 17 a , a connection portion 18 and an opening portion 19 . The collecting line 17a is a plurality of linear members that are not electrically connected to each other at the portion adjacent to the negative electrode mixture layer 22 and in contact with the negative electrode active material. The collector line 17a may have a square or rectangular cross-sectional shape, or a polygonal column such as a cylindrical column, an elliptical column, a hexagonal column, or an octagonal column. The connecting portion 18 is a continuous member that connects the plurality of collecting wires 17a in parallel outside where the collecting wires 17a and the negative electrode active material are not in contact with each other. The connecting portion 18 is a foil-like or plate-like member whose longitudinal direction is the arrangement direction of the collecting lines 17a. The opening 19 is a space that communicates with the separator 13 and is formed between the collecting lines 17a. The negative electrode current collector 17 has a plurality of openings 19 . The opening 19 is filled with the negative electrode mixture layer 22 . The negative electrode current collector 17 may have the same shape as the positive electrode current collector 14, or may have a different shape.

In addition to copper, nickel, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al—Cd alloy, etc., the collecting line 17a is made of materials such as For example, copper or the like whose surface has been treated with carbon, nickel, titanium, silver, or the like can also be used. For these, it is also possible to oxidize the surface. It is preferable that the width t of the collecting line 17a is in the range of 100 μm to 500 μm, and the width s of the opening 19 is in the range of 100 μm to 500 μm. The width t and the width s may be the same value or different values, but considering the support during lamination, the same value is preferable. The width t of the collecting line 17a is more preferably 200 μm or more, and may be 250 μm or more. Further, the width t of the collector line 17a is more preferably 400 μm or less, and may be 300 μm or less. The width s of the opening 19 is more preferably 200 μm or more, and may be 250 μm or more. Further, the width s of the opening 19 is more preferably 400 μm or less, and may be 300 μm or less. The length L of the collecting line 17a may be appropriately selected according to the characteristics required for the power storage device 20, and may be, for example, 5 cm or more, or 10 cm or more and 20 cm or more. Also, the length of the opening 19 may be the same as the length L of the collecting line 17a.

The connecting portion 18 may be configured such that the collecting lines 17a having a number N of 100 or more are connected in parallel, or the collecting lines 17a having a number N of 200 or more or 500 or more may be connected in parallel. . Since the resistance applied to the single cell 23 via the connection portion 18 is determined according to the number N of parallel connections, the number N of parallel connections of the collecting lines 17a, the connection portions 18 and The volume resistivity of the collecting line 17a may be appropriately set. In addition, since the amount of the negative electrode active material per unit volume decreases as the number N of the collecting lines 17a increases, the number N of the collecting lines 17a may be appropriately set in consideration of the energy density. The negative electrode current collector 17 may have a volume resistivity of 1.0×10 ⁻⁷ Ωm or less. Further, the negative electrode current collector 17 may have a volume resistivity of 5.0×10 ⁻⁸ Ωm or less, or may have a volume resistivity of 2.0×10 ⁻⁸ Ωm or less. The volume resistivity of the collecting line 17a and the connection portion 18 may be the same or different.

The opening 16 preferably has an area ratio of 20% or more. The aperture ratio refers to the ratio of the area of the opening 16 to the area of the entire region of the positive electrode current collector 14 including the collecting line 14a, excluding the area of the connecting portion 15. FIG. From the viewpoint of conduction of carrier ions, the aperture ratio is preferably as large as possible, and from the viewpoint of conductivity, the smaller one is preferred. The aperture ratio is preferably 30% or more, more preferably 40% or more, and may be 50% or more. The aperture ratio is preferably 80% or less, more preferably 70% or less, and may be 60% or less. The aperture 19 may have the same aperture ratio as the aperture 16, or may have a different aperture ratio. The opening 19 is assumed to be the same as the opening 16, and detailed description thereof will be omitted.

(storage device)
As shown in FIG. 2, the electricity storage device 20 includes a structure 10, a positive electrode mixture layer 21 formed on the positive electrode collector 14 side, and a negative electrode mixture layer 22 formed on the negative electrode collector 17 side. , is equipped with The positive electrode 25 is composed of the positive electrode current collector 14 and the positive electrode mixture layer 21 , and the negative electrode 26 is composed of the negative electrode current collector 17 and the negative electrode mixture layer 22 . The electric storage device 20 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. Examples of carrier ions of the electricity storage device 20 include alkali metal ions such as lithium ions, sodium ions, and potassium ions, group 2 ions such as magnesium ions, strontium ions, and calcium ions. In addition, one or more of the positive electrode 25, the negative electrode 26, and the separator 13 of the electric storage device 20 may contain an ion-conducting medium. Here, for convenience of description, a lithium ion secondary battery using lithium ions as a carrier will be described below as a main example.

The positive electrode 25 may have a positive electrode mixture layer 21 and a positive electrode current collector 14 . The positive electrode mixture layer 21 may contain a positive electrode active material, and optionally a conductive material and a binder. For the positive electrode 25, for example, a positive electrode active material, a conductive material, and a binder are mixed, and an appropriate solvent is added to form a paste-like positive electrode mixture. However, if necessary, it may be formed by compression to increase the electrode density. Examples of the positive electrode active material include materials capable of intercalating and deintercalating lithium, which is a carrier. Examples of positive electrode active materials include compounds containing lithium and a transition metal, such as oxides containing lithium and a transition metal element, and phosphate compounds containing lithium and a transition metal element. Specifically, a lithium-manganese composite oxide having a basic composition formula of Li _(1-x) MnO ₂ (0≦x≦1, etc., hereinafter the same) or Li _(1-x) Mn ₂ O ₄ , etc., basic composition A lithium cobalt composite oxide having a formula such as Li _{(1-x) CoO2} , a lithium nickel composite oxide having a basic composition formula such as Li _{(1-x) NiO2} , and a basic composition formula of Li _(1-x) CoaNibMncO2 (a _> 0, b>0, c>0, _a + _{b +} c ₌ 1), _{Li (1-x) CoaNibMncO4 (} 0<a<1, 0<b <1, 1 ≤ c < 2, a + b + c = 2), etc., lithium vanadium composite oxides with a basic composition formula of LiV ₂ O ₃ , etc., basic composition formulas of V ₂ O ₅ , etc. A transition metal oxide or the like can be used. Also, a lithium iron phosphate compound having a basic compositional formula of LiFePO ₄ or the like can be used as the positive electrode active material. Among these, lithium-cobalt-nickel-manganese _composite oxides such _as LiCo1 _{/ 3Ni1} / _{3Mn1 / 3O2} and _{LiNi0.4Co0.3Mn0.3O2} are preferable. In addition, the "basic composition formula" means that other elements such as Al and Mg may be included.

The conductive material is not particularly limited as long as it is an electronically conductive material that does not adversely affect the battery performance of the positive electrode. One or a mixture of two or more of ketjen black, carbon whiskers, needle coke, carbon fibers, metals (copper, nickel, aluminum, silver, gold, etc.) can be used. Among these, carbon black and acetylene black are preferable as the conductive material from the viewpoint of electronic conductivity and coatability. The binder plays a role of binding the active material particles and the conductive material particles, and examples thereof include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-containing resin such as fluororubber, polypropylene, Thermoplastic resins such as polyethylene, ethylene propylene diene rubber (EPDM), sulfonated EPDM rubber, natural butyl rubber (NBR) and the like can be used alone or as a mixture of two or more. Cellulose-based or styrene-butadiene rubber (SBR) aqueous dispersions, which are water-based binders, can also be used. Examples of solvents for dispersing the positive electrode active material, conductive material, and binder include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, and N,N-dimethylaminopropylamine. , ethylene oxide, and tetrahydrofuran can be used. Alternatively, a dispersant, a thickener, or the like may be added to water, and the active material may be slurried with a latex such as SBR. As the thickening agent, for example, polysaccharides such as carboxymethyl cellulose and methyl cellulose can be used singly or as a mixture of two or more. Application methods include, for example, roller coating such as applicator roll, screen coating, doctor blade method, spin coating, and bar coater, and any thickness and shape can be obtained using any of these methods.

The content of the positive electrode active material in the positive electrode 25 is preferably larger, preferably 70% by mass or more, more preferably 80% by mass or more, based on the total mass of the positive electrode 25 . The content of the conductive material is preferably in the range of 0% by mass or more and 20% by mass or less, more preferably in the range of 0% by mass or more and 10% by mass or less with respect to the total mass of the positive electrode 25 . Within such a range, a decrease in battery capacity can be suppressed and sufficient conductivity can be imparted. Further, the content of the binder is preferably in the range of 0.1% by mass or more and 5% by mass or less with respect to the total mass of the positive electrode 25, and is in the range of 0.2% by mass or more and 3% by mass or less. is more preferable.

Negative electrode 26 includes negative electrode mixture layer 22 and negative electrode current collector 17 . The negative electrode 26 may be formed by adhering the negative electrode mixture layer 22 and the negative electrode current collector 17 together. A paste-like negative electrode composite material may be formed by coating and drying on the negative electrode current collector 17 side of the structure 10 and, if necessary, compressing to increase the electrode density. The negative electrode mixture layer 22 may contain a negative electrode active material, a conductive material, and a binder. Examples of negative electrode active materials include inorganic compounds such as lithium, lithium alloys and tin compounds, carbonaceous materials capable of intercalating and deintercalating lithium ions, composite oxides containing multiple elements, and conductive polymers. Examples of carbonaceous materials include cokes, vitreous carbons, graphites, non-graphitizable carbons, pyrolytic carbons, and carbon fibers. Among them, graphites such as artificial graphite and natural graphite have an operating potential close to that of metallic lithium, can be charged and discharged at a high operating voltage, and suppress self-discharge when lithium salt is used as a supporting salt. Moreover, the irreversible capacity during charging can be reduced, which is preferable. Examples of composite oxides include lithium-titanium composite oxides and lithium-vanadium composite oxides. Among them, carbonaceous materials are preferable as the negative electrode active material from the viewpoint of safety. As the conductive material, binder, solvent, and the like used for the negative electrode 26, those exemplified for the positive electrode 25 can be used.

The content of the negative electrode active material in the negative electrode 26 is preferably larger, preferably 70% by mass or more, more preferably 80% by mass or more, based on the total mass of the negative electrode 26 . The content of the conductive material is preferably in the range of 0% by mass or more and 20% by mass or less, more preferably in the range of 0% by mass or more and 10% by mass or less with respect to the total mass of the negative electrode 26 . Within such a range, a decrease in battery capacity can be suppressed and sufficient conductivity can be imparted. In addition, the content of the binder is preferably in the range of 0.1% by mass or more and 5% by mass or less with respect to the entire mass of the negative electrode 26, and is in the range of 0.2% by mass or more and 3% by mass or less. is more preferable.

A non-aqueous electrolytic solution containing a supporting salt, a non-aqueous gel electrolytic solution, or the like can be used as the ion-conducting medium. Examples of the solvent for the non-aqueous electrolytic solution include carbonates, esters, ethers, nitriles, furans, sulfolanes, dioxolanes, and the like, and these can be used singly or in combination. Specifically, the carbonates include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate, vinylene carbonate, butylene carbonate, and chloroethylene carbonate, dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate, ethyl - chain carbonates such as n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate and t-butyl-i-propyl carbonate; cyclic esters such as γ-butyl lactone 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. sulfolane such as sulfolane and tetramethylsulfolane; and dioxolane such as 1,3-dioxolane and methyldioxolane. A supporting salt containing ions that are carriers of the structure 10 may be dissolved in the electrolytic solution. Examples of supporting salts include _LiPF6 , _{LiBF4 ,} LiAsF6, _LiCF3SO3 , LiN( _{CF3SO2 ) 2} , LiC( _{CF3SO2 ) 3 ,} LiSbF6, _{LiSiF6 , LiAlF4} , LiSCN, LiClO ₄ , LiCl, LiF, LiBr, LiI, LiAlCl ₄ and the like. Among them, 1 selected from the group consisting of inorganic salts such as LiPF ₆ , LiBF ₄ and LiClO ₄ and organic salts such as LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ and LiC(CF ₃ SO _{2 )} 3 From the viewpoint of electrical properties, it is preferable to use a species or a combination of two or more salts. The concentration of the supporting salt in the electrolytic solution is preferably 0.1 mol/L or more and 5 mol/L or less, more preferably 0.5 mol/L or more and 2 mol/L or less.

The slow discharge function of the electric storage device 20 at the time of internal short circuit from the fully charged state is preferably longer from the viewpoint of safety, for example, preferably 30 minutes or more, more preferably 1 hour or more. Preferably, it is more preferably 2 hours or more. If this slow discharge function lasts longer, it is possible to further suppress rapid discharge at the time of a partial short circuit inside the cell, and to ensure safety. From the viewpoint of energy density, such as increasing the resistance of the structure 10, the slow discharge function may be performed for 5 hours or less.

In the electricity storage device 20, as shown in FIGS. 1 and 2, the collecting line 14a and the collecting line 17a are arranged to face each other with the separator 13 interposed therebetween. and the collecting line 17a may be arranged with the separator 13 interposed therebetween. The structural body 10B and the single cell 23B are the same as the structural body 10 and the single cell 23 except for the position of the collecting line. Considering the conduction of carrier ions, the electricity storage device 20 is preferable.

The shape of the electricity storage device 20 is not particularly limited, and examples thereof include a coin shape, a button shape, a sheet shape, a laminated shape, a cylindrical shape, a flat shape, a rectangular shape, and the like. Also, a plurality of such batteries may be connected in series and applied to a large-sized battery used in an electric vehicle or the like.

(Method for manufacturing power storage device)
A method for manufacturing an electric storage device includes a positive electrode structure manufacturing step, a negative electrode structure manufacturing step, and a stacking step, and may further include an ion conductive medium impregnation step. Also, the first step may include a structure preparation step. In this manufacturing method, it is assumed that the structures 10 and 10B and the electric storage devices 20 and 20B described above can be appropriately used, and detailed description thereof will be omitted.

(Structure preparation step)
In this step, the structure 10 is prepared. As described above, the structure 10 includes the separator 13, the positive electrode current collector 14 having the opening 16 formed on the first surface 11 of the separator 13 and communicating with the separator 13, and the second surface 12 of the separator 13. and a negative electrode current collector 17 having an opening 19 which is formed in the separator 13 and communicates with the separator 13 . In this step, the positive electrode current collector 14 may be formed on the first surface 11 of the separator 13 and the negative electrode current collector 17 may be formed on the second surface 12 of the separator 13 to produce the structure 10 .

(Positive electrode structure manufacturing process)
In this step, a positive electrode mixture layer 21 is formed on the positive electrode current collector 14 side of the structure 10 to obtain a positive electrode structure. The positive electrode mixture layer 21 can be formed by appropriately adopting the material described for the electricity storage device 20 . The thickness of the positive electrode mixture layer 21 may be, for example, 50 μm or more, 80 μm or more, or 100 μm or more. Also, the thickness of the positive electrode mixture layer 21 may be 200 μm or less, 150 μm or less, or 120 μm or less. The thickness of the positive electrode mixture layer 21 may be appropriately selected according to the characteristics of the electricity storage device 20 .

(Negative electrode structure manufacturing step)
In this step, the negative electrode mixture layer 22 is formed on the negative electrode current collector 17 side of the structure 10 to obtain the negative electrode structure. The negative electrode mixture layer 22 can be formed by appropriately adopting the material described for the electricity storage device 20 . The thickness of the negative electrode mixture layer 22 may be, for example, 50 μm or more, 80 μm or more, or 100 μm or more. Also, the thickness of the negative electrode mixture layer 22 may be 200 μm or less, 150 μm or less, or 120 μm or less. The thickness of the negative electrode mixture layer 22 may be appropriately selected according to the characteristics of the electricity storage device 20 .

(Lamination process)
In this step, a process of stacking the positive electrode structure and the negative electrode structure obtained above is performed. In the stacking step, the layers are stacked such that the negative electrode mixture layer 22 of the negative electrode structure faces the negative electrode current collector 17 side of the positive electrode structure. Alternatively, the layers are laminated so that the positive electrode mixture layer 21 of the positive electrode structure faces the positive electrode current collector 14 side of the negative electrode structure. In this step, the laminated body obtained by lamination may be pressure-pressed. By applying pressure, the opening 16 of the positive electrode current collector 14 and the opening 19 of the negative electrode current collector 17 are filled with the mixture layer.

(Ion conducting medium impregnation step)
In this step, the laminate thus obtained is placed in a cell case, and the laminate is impregnated with an ion-conducting medium, especially an electrolyte. In this laminate, the electrolytic solution can pass through the openings 16 of the positive electrode current collector 14 and the openings 19 of the negative electrode current collector 17, and the impregnation can be performed quickly.

In the structure 10 and the electric storage device 20 detailed above, the manufacturing process can be simplified as much as possible. The reason why such an effect is obtained is presumed as follows. For example, a conventional electricity storage device such as a lithium battery composed of sheet-like electrodes requires three types of separators, a positive electrode current collector foil, and a negative electrode current collector foil. Since there is only one type of structure, which is a separator with an electric body formed thereon, it is easy to handle. In the conventional structure, the positive electrode mixture is applied to the surface of the positive electrode current collector, and then the positive electrode mixture is applied again to the back surface of the positive electrode current collector. is applied, and then the negative electrode mixture is applied again to the back surface of the negative electrode current collector to obtain positive/negative electrodes. Therefore, in the conventional sheet-like electrode, it is necessary to apply the composite material four times. Since the negative electrode mixture is applied to the electric body side and these are laminated, the application of the mixture is only required twice. In addition, in the conventional sheet-like electrode, three steps of laminating a separator on a positive electrode current collector formed with a positive electrode mixture and further laminating a negative electrode current collector formed with a negative electrode mixture are required. In the present disclosure, only two steps of laminating the structure having the negative electrode composite material on the structure having the positive electrode composite material formed thereon are required. In addition, in the conventional structure, since the metal current collector is in the form of a foil, the electrolytic solution permeation path to the electrode after lamination is only in the surface direction, and it takes time to inject the electrolytic solution. Since the positive and negative electrode current collectors have openings that communicate with the separator, the electrolyte permeates the current collector not only in the surface direction but also in the thickness direction, so that the permeation of the electrolyte can be performed more smoothly. In addition, in the present disclosure, the current collector of the positive and negative electrodes has an opening, and the proportion of the current collector in the laminated electrode is reduced, so that the proportion of the positive and negative electrode active materials is relatively increased, and the energy Density can be improved. Thus, the structure of the present disclosure can simplify the manufacturing process as much as possible. In addition, in the structure 10, by arranging the positive/negative current collectors having a comb tooth structure on the front and back of the separator, the current path during an internal short circuit has a high resistance, and current concentration during an internal short circuit is suppressed. Greatly improves safety.

It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present disclosure.

For example, in the above-described embodiment, the carrier of the electricity storage device is lithium ions, but it is not particularly limited to this, and alkali metal ions such as sodium ions and potassium ions, group 2 element ions such as calcium ions and magnesium ions can also be used. good. Moreover, the positive electrode active material may contain carrier ions. Moreover, although the electrolytic solution is a non-aqueous electrolytic solution, it may be an aqueous electrolytic solution.

In the above-described embodiments, the positive electrode active material is a transition metal composite oxide, but is not particularly limited, and may be, for example, a carbon material used in capacitors. Examples of carbon materials include, but are not limited to, activated carbons, cokes, vitreous carbons, graphites, non-graphitizable carbons, pyrolytic carbons, carbon fibers, carbon nanotubes, and polyacenes. Among these, activated carbons exhibiting a high specific surface area are preferred. Activated carbon as the carbon material preferably has a specific surface area of 1000 m ² /g or more, 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, more preferably 2000 m ² /g or less, for ease of production. The positive electrode is thought to store electricity by adsorbing and desorbing at least one of the anions and cations contained in the ion-conducting medium. It is also possible to store electricity by

In the above-described embodiment, the positive electrode current collector 14 and the negative electrode current collector 17 are assumed to have a comb tooth shape, but are not particularly limited to this as long as they have openings. The body 14 and the negative electrode current collector 17 may be a sheet-like current collector having a plurality of circular, elliptical, rectangular, polygonal, or other openings formed therein. Also in this structure, there is a space that communicates with the separator 13 from the opening, and the separator, the positive electrode current collector, and the negative electrode current collector 17 are integrated, so that the manufacturing process can be simplified as much as possible.

Examples in which the structure, the electricity storage device, and the method for manufacturing the electricity storage device described above are specifically examined will be described below as examples.

A structure of the present disclosure and an electricity storage device using the same are taken as examples, and an electricity storage device having a general coated electrode using a sheet-like current collector foil is taken as a comparative example. The structure of the example used a polyethylene separator having a thickness of 15 μm. The positive electrode current collector 14 had a comb tooth shape, was made of Al, had a length of 70 mm, a width t of 335 μm, and a thickness of 7 μm. The negative electrode current collector 17 had a comb tooth shape, was made of Cu, and had a length of 70 mm, a width t of 200 μm, and a thickness of 7 μm. In the electric storage device 20, the thickness of the positive electrode mixture layer 21 was set to 120 μm, and the thickness of the negative electrode active material layer was set to 100 μm. A polyethylene separator having a thickness of 15 μm was used in the comparative example. The positive electrode current collector had a sheet shape, was made of Al, and had a thickness of 10 μm. The negative electrode current collector had a sheet shape, was made of Cu, and had a thickness of 20 μm. In addition, in the electricity storage device of the comparative example, the thickness of the positive electrode mixture layer was set to 60 μm, and the thickness of the negative electrode active material layer was set to 50 μm.

FIG. 5 is an explanatory diagram of the number of constituent members in an example and a comparative example. As shown in FIG. 5, in the comparative example composed of conventional sheet-like electrodes, three kinds of separators, positive electrode current collector foils, and negative electrode current collector foils are required. Since there is only one type of structure, which is a separator with a current collector formed thereon, it is easy to handle. In addition, the reduction in the number of parts can simplify the management of parts at the time of manufacturing in terms of stock space and inventory management, etc., and can also reduce costs.

FIG. 6 is an explanatory diagram of the number of times of coating in Examples and Comparative Examples. As shown in FIG. 6, in the comparative example of the conventional structure, the positive electrode mixture was applied to the surface of the positive electrode current collector, and then the positive electrode mixture was applied again to the back surface of the positive electrode current collector. The surface of the current collector is coated with the negative electrode mixture, and then the back surface of the negative electrode current collector is coated with the negative electrode mixture again to obtain positive/negative electrodes. Therefore, in the comparative example, it is necessary to apply the composite material four times. On the other hand, in the examples, the positive electrode mixture is applied to the positive electrode current collector side of the structure, and the negative electrode mixture is applied to the negative electrode current collector side of another structure. . At this time, the positive electrode mixture and the negative electrode mixture may be formed to have a thickness twice that of the comparative example. In this way, since the step of forming the composite material layer can be reduced, the manufacturing process can be simplified as much as possible. The coating of the composite layer, including drying, takes a long process and a long process time, and requires a large amount of energy. can also

FIG. 7 is an explanatory diagram of the number of times of lamination in an example and a comparative example. As shown in FIG. 7, in the comparative example of the conventional structure, three steps of laminating a separator on a positive electrode current collector formed with a positive electrode mixture and further laminating a negative electrode current collector formed with a negative electrode mixture are required. be. On the other hand, in the embodiment, only two steps are required to stack the structure having the negative electrode composite material on the structure having the positive electrode composite material formed thereon. As described above, in the embodiment, the number of assembling processes can be reduced, so that the manufacturing process can be simplified as much as possible. In addition, the assembly work in the stacking process must be performed with high positional accuracy, and an increase in the number of such processes takes time and increases the possibility of producing defective products. This reduction in assembly work is extremely effective, and along with this, it is also possible to reduce costs.

FIG. 8 is an explanatory diagram of impregnation with an electrolytic solution in an example and a comparative example. As shown in FIG. 8, in the comparative example of the conventional structure, since the metal current collector is in the form of a foil, there is only a path for the electrolyte to permeate into the electrode after lamination, and it takes time to inject the electrolyte. On the other hand, in the examples, since the positive and negative electrode current collectors have openings communicating with the separator, the electrolyte permeates the current collector not only in the surface direction but also in the thickness direction, and the electrolyte permeates more smoothly. It can be carried out. In general, the shape of the electrode is 10 cm to several tens of cm in the horizontal direction of FIG. 8 and about 1 cm or less in the vertical direction. Therefore, in the comparative example in which the electrolytic solution cannot permeate from above and below, it takes an extremely long time to inject the solution. On the other hand, in the embodiment, since the liquid injection time can be significantly shortened, the shortening of the liquid injection time is extremely effective, and along with this, cost reduction can also be achieved. In addition, in the examples, the current collectors of the positive and negative electrodes have openings, and the ratio of the current collectors in the laminated electrode is reduced, so the ratio of the positive electrode/negative electrode active materials is relatively increased, and the energy consumption is increased. Density can also be improved.

FIG. 9 is an explanatory diagram of the embodiment when a partial short circuit occurs. As shown in FIG. 9, even if the collecting lines are arranged in a striped pattern, normal charging and discharging can be performed without any problem. The current tends to concentrate on the collecting line near the point. However, since a single collector wire is much smaller in volume than a continuous current collector foil, even if a member with the same volume resistivity is used, the resistance is increased. As a result, the current value flowing concentratedly at the short-circuited portion becomes small, and discharge occurs slowly over a long period of time, that is, so-called gradual discharge. Although the resistance of one collecting wire increases, the current flowing through one collecting wire during normal use is a small current corresponding only to the electrodes in the vicinity of the current collector, so that there is no problem. In other words, the current collection resistance within the electrode in the entire cell is reduced to a value obtained by dividing one current collection resistance by the number of multiple current collectors. In other words, by connecting a large number of relatively high-resistance collection lines in parallel, the current collection resistance of the entire cell is designed to be low, enabling smooth charging and discharging, and if an internal short circuit occurs somewhere, the high resistance Since the current passes through the collector wire, it becomes a gradual discharge, and a high level of safety can be ensured.

As described above, in the structure and the electric storage device of the example, the manufacturing process can be simplified as much as possible by arranging the positive/negative current collectors having openings on the front and back of the separator. Moreover, in the embodiment, manufacturing time and management of materials can be reduced. Furthermore, in the embodiment, the energy density can be further increased, and the current path at the time of an internal short circuit has a high resistance, so that the current concentration at the time of an internal short circuit is suppressed, so that the safety can be greatly improved.

It goes without saying that the present disclosure is by no means limited to the above-described embodiments, and can be embodied in various forms as long as they fall within the technical scope of the present disclosure.

Reference Signs List 10, 10B, structure, 11 first surface, 12 second surface, 13 separator, 14 positive electrode collector, 14a collector wire, 15 connecting portion, 16 opening, 17 negative electrode collector, 17a collector wire, 18 connection Part 19 Opening 20, 20B Power storage device 21 Positive electrode mixture layer 22 Negative electrode mixture layer 23, 23B Single cell 25 Positive electrode 26 Negative electrode M, N Number L Length t Width s Width .

Claims (7)

A structure used in an electricity storage device,
a separator;
a positive electrode current collector having an opening formed on the first surface of the separator and communicating with the separator;
a negative electrode current collector having an opening formed on the second surface of the separator and communicating with the separator;
A struct with 2. The structure according to claim 1, wherein the positive electrode current collector and/or the negative electrode current collector has an opening ratio of 20% or more in area ratio. 3. The structure according to claim 1, wherein said positive electrode current collector and/or said negative electrode current collector has a comb tooth shape. The positive electrode current collector has a positive electrode current collector that does not have the opening at the end,
The negative electrode current collector has a negative electrode current collector that does not have the opening at the end,
4. The structure according to any one of claims 1 to 3, wherein the positive electrode current collecting portion and the negative electrode current collecting portion are formed on opposite sides. Any one or more of a positive electrode mixture layer formed on the positive electrode collector side and/or a negative electrode mixture layer formed on the negative electrode collector side, according to any one of claims 1 to 4. or the structure according to item 1. A structure according to any one of claims 1 to 5;
a positive electrode mixture layer formed on the side of the positive electrode current collector;
a negative electrode mixture layer formed on the negative electrode current collecting portion side;
A storage device with A method for manufacturing an electricity storage device,
a separator, a positive current collector having an opening formed on a first surface of the separator and communicating with the separator, and a negative current collector having an opening formed on a second surface of the separator and communicating with the separator. A positive electrode structure manufacturing step of forming a positive electrode mixture layer on the positive electrode current collector side of the structure provided with a positive electrode structure to obtain a positive electrode structure;
a negative electrode structure producing step of forming a negative electrode mixture layer on the negative electrode current collector side of the structure to obtain a negative electrode structure;
A stacking step of stacking the positive electrode structure and the negative electrode structure;
A method of manufacturing an electricity storage device comprising:

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