WO2012011351A1 - 二次電池用多孔質電極 - Google Patents
二次電池用多孔質電極 Download PDFInfo
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- WO2012011351A1 WO2012011351A1 PCT/JP2011/064236 JP2011064236W WO2012011351A1 WO 2012011351 A1 WO2012011351 A1 WO 2012011351A1 JP 2011064236 W JP2011064236 W JP 2011064236W WO 2012011351 A1 WO2012011351 A1 WO 2012011351A1
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- electrode
- domain structure
- current collector
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- secondary battery
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- H—ELECTRICITY
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
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- H—ELECTRICITY
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/581—Chalcogenides or intercalation compounds thereof
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/70—Carriers or collectors characterised by shape or form
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0438—Processes of manufacture in general by electrochemical processing
- H01M4/045—Electrochemical coating; Electrochemical impregnation
- H01M4/0452—Electrochemical coating; Electrochemical impregnation from solutions
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- H—ELECTRICITY
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/8605—Porous electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/8605—Porous electrodes
- H01M4/8626—Porous electrodes characterised by the form
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/023—Porous and characterised by the material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0247—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the form
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
- H01M8/1018—Polymeric electrolyte materials
- H01M8/1058—Polymeric electrolyte materials characterised by a porous support having no ion-conducting properties
- H01M8/1062—Polymeric electrolyte materials characterised by a porous support having no ion-conducting properties characterised by the physical properties of the porous support, e.g. its porosity or thickness
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- the present invention relates to an electrode that can be preferably used for a secondary battery.
- lithium ion secondary batteries are superior to other secondary batteries in terms of these required characteristics, and are increasingly being adopted for portable devices.
- lithium ion secondary batteries In a lithium ion secondary battery, during discharge, lithium present in the negative electrode is oxidized and released as lithium ions, while at the positive electrode, lithium ions are reduced and stored as lithium compounds. At the time of charging, lithium ions are reduced and stored as lithium in the negative electrode, while lithium compounds existing in the positive electrode are oxidized and released as lithium ions.
- lithium ions move between the positive electrode and the negative electrode, and are occluded as lithium or a lithium compound at any electrode.
- a carbon material such as graphite is used as a negative electrode material of such a lithium ion secondary battery.
- a carbon material such as graphite is used.
- graphite when graphite is used as a negative electrode material, lithium is occluded between graphite layers, so that charging / discharging is performed.
- graphite since graphite has the principle of charge / discharge by intercalation of lithium ions into graphite crystals, a charge / discharge capacity of 372 mAh / g or more cannot be obtained when calculated from LiC 6 which is the maximum lithium introduction compound. There is a drawback.
- Patent Document 1 proposes a negative electrode for a lithium secondary battery made of a metal that can be alloyed with lithium and having a porous structure.
- a negative electrode By using such a negative electrode, the internal stress accompanying the volume change when the negative electrode material forms an alloy with lithium is relieved, and charge / discharge cycle characteristics can be improved.
- Non-Patent Document 1 proposes that the porous electrode described in Patent Document 1 is divided into a plurality of columnar structures separated from each other on the surface of the current collector. According to such a negative electrode, the internal stress of the negative electrode during charge / discharge is further relaxed, so that the charge / discharge cycle characteristics can be further improved.
- the lifetime is improved as compared with conventional alloy negative electrodes.
- a porous negative electrode still has an effect due to internal stress in the negative electrode, and there is room for improvement in that the occurrence of cracks in the negative electrode due to repeated charge and discharge is observed.
- the negative electrode described in Non-Patent Document 1 the occurrence of cracks in the negative electrode is greatly suppressed, and the lifetime is greatly improved.
- the negative electrode described in Non-Patent Document 1 is formed as a collection of cylindrical structures separated from each other on the surface of the current collector, there are many unused portions on the surface of the current collector where the negative electrode is not formed. There was room for improvement in terms of capacity.
- the present invention has been made in view of the above circumstances, and an object thereof is to provide an electrode that has good charge / discharge cycle characteristics and can improve the capacity of a secondary battery.
- the present inventors formed electrodes on the surface of the current collector as a set of a plurality of porous domain structures separated from each other.
- the inventors have found that by forming a polygonal shape having no acute angle and having a maximum diameter of 120 ⁇ m or less, both the charge / discharge cycle characteristics and the battery capacity can be improved, and the present invention has been completed.
- the present invention is formed as a set of a plurality of porous domain structures spaced from each other on the surface of a current collector, and the porous domain structure has a polygonal shape having no acute angle in plan view, and the polygonal shape This is an electrode having a maximum diameter of 120 ⁇ m or less.
- an electrode that has good charge / discharge cycle characteristics and can improve the capacity of a secondary battery.
- FIGS. 4A to 4F are perspective views sequentially illustrating an example of a manufacturing procedure in the electrode according to the first embodiment of the present invention.
- FIG. 1 is a perspective view showing a first embodiment of the electrode of the present invention.
- FIG. 2 is a plan view showing the first embodiment of the electrode of the present invention.
- FIG. 3 is an enlarged perspective view showing a domain structure in the first embodiment of the electrode of the present invention.
- the electrode 1 is formed on the surface of the current collector 3 as a set of a plurality of domain structures 2 separated from each other. In each of these domain structures 2, a positive electrode reaction or a negative electrode reaction occurs, and current generated by these reactions is collected in the current collector 3.
- Examples of the battery in which the electrode 1 of the present invention is used include a secondary battery that can be charged and discharged.
- a secondary battery is not particularly limited, but includes a lithium ion secondary battery.
- an electrode of a lithium ion secondary battery will be described as an embodiment of the present invention.
- the present invention is not limited to this, and the discharge of ions from the electrodes or the ions to the electrodes accompanying charging / discharging. It is preferably applied to a secondary battery that causes occlusion.
- the electrode 1 for the lithium ion secondary battery of the present embodiment may be either a negative electrode or a positive electrode.
- the said electrode 1 is comprised with the metal or alloy alloyed with lithium.
- metals or alloys include tin, lead, silver, and alloys containing these metals. Among these, in consideration of material costs, tin or a tin alloy such as Si—Ni is practical.
- the content of tin in the negative electrode may be in the range of 5% by mass to 99.995% by mass.
- a metal chalcogen compound that can occlude and release lithium ions during charge and discharge is preferably used as the electrode 1.
- metal chalcogen compounds include vanadium oxide, vanadium sulfide, molybdenum oxide, molybdenum sulfide, manganese oxide, chromium oxide, titanium oxide, titanium sulfide, and the like. And composite oxides and sulfides.
- LiMY 2 (M is a transition metal such as Co and Ni, Y is a chalcogen atom such as O and S), LiM 2 Y 4 (M is Mn, Y is O), oxide such as WO 3 , CuS Further, sulfides such as Fe 0.25 V 0.75 S 2 and Na 0.1 CrS 2 , phosphorus such as NiPS 8 and FePS 8 , sulfur compounds, and selenium compounds such as VSe 2 and NbSe 3 are also preferably used. .
- the electrode 1 is formed on the surface of the current collector 3.
- Any known material can be used as the current collector 3 as long as it is a material having electrical conductivity. Examples of such a material include copper, nickel, stainless steel, etc., but copper is preferably used.
- the current collector 3 is a metal that is alloyed with the electrode 1 by, for example, heating or the like, in the vicinity of the boundary between the domain structure 2 constituting the electrode 1 and the current collector 3, An alloy layer (not shown) of the metal constituting the domain structure 2 and the metal constituting the current collector 3 can be formed.
- the adhesion between the domain structure 2 and the current collector 3 is improved, and the domain structure 2 is detached from the current collector 3 due to expansion or contraction of the domain structure 2 during charge / discharge. It is preferable because separation can be suppressed.
- the current collector 3 is practically plate-shaped or foil-shaped.
- the polarities of the domain structures 2 provided on the surface of the current collector 3 are the same. Therefore, the aggregate of the domain structure 2 can be handled as one electrode. That is, the electrode 1 that is an aggregate of the domain structures 2 is either a positive electrode or a negative electrode. When the electrode 1 is a negative electrode, a positive electrode (not shown) is provided via a separator or the like to form a battery. Further, when the electrode 2 is a positive electrode, a negative electrode (not shown) is provided via a separator or the like to form a battery.
- the domain structure 2 constituting the electrode 1 is formed as a polygonal shape having no acute angle in plan view from above the current collector 3.
- the domain structure 2 of the present embodiment penetrates to the surface of the current collector 3, and a resist film having a through-hole having the same shape as the domain structure 2 in a plan view is used as a template for the domain structure in the through-hole. It is formed by filling the metal constituting 2.
- the through-hole serving as the mold includes an acute angle portion, when the metal is filled in the through-hole, the stress generated in the mold concentrates on the acute-angled portion and a crack is generated in the mold. May not be formed into the intended shape. From such a viewpoint, in the present invention, the domain structure 2 is formed as a polygonal shape having no acute angle in plan view from above the current collector 3.
- the shape of the domain structure 2 includes a polygonal column shape having a polygonal cross section without an acute angle, and examples thereof include a quadrangular column, a pentagonal column, a hexagonal column, a heptagonal column, and an octagonal column. Among these, it is preferable that it is a polygonal column shape which is a rectangle, a square, or a regular hexagon by planar view from the upper direction of the electrical power collector 3, The reason is mentioned later.
- the domain structure 2 is a regular hexagon in plan view from above the current collector 3, and the separation width of each domain structure 2 is the same. A certain electrode 1 will be described.
- the electrode 1 is composed of a plurality of domain structures 2 arranged in a honeycomb shape in plan view from above the current collector 3.
- the height of the domain structure 2 may be appropriately determined according to the dimensions required for the electrode 1, the charge / discharge capacity, and the like, and examples include 18 ⁇ m to 50 ⁇ m.
- the plurality of domain structures 2 constituting the electrode 1 are arranged apart from each other as shown in FIG. 1 and are each formed as a porous body as shown in FIG.
- the This is one of the points of the present invention.
- an electrode is formed of a metal material such as an alloy in a secondary battery that releases ions from or is occluded into an electrode, such as a lithium ion secondary battery, the electrode is charged and discharged. At this time, a large internal stress is generated due to a volume change accompanying alloying and dealloying, and the internal charge reduces the powder charge and discharge capacity thereafter.
- the inventors of the present invention have caused such internal stress accompanying the volume change due to the electrode in the conventional secondary battery being formed as a lump structure without a gap such as a foil shape or a plate shape. It has been found that these problems can be solved if the electrode 1 is formed as an assembly of a plurality of porous domain structures 2 spaced apart from each other.
- the domain structure 2 of the present embodiment is formed as a porous body having a plurality of pores 21, as shown in FIG.
- these holes are provided in a substantially spherical shape, and the substantially spherical holes are provided so as to be closest packed, but the present invention is not limited to this.
- the metal material 22 constituting the domain structure 2 is included in the domain structure 2 even when the volume change occurs due to charge / discharge.
- the holes 21 absorb the volume change of the metal material 22 and reduce the generation of internal stress. That is, when the metal material 22 constituting the domain structure 2 is expanded by charging, the holes 21 included in the domain structure 2 provide a space for the metal material 22 to expand so as to fill the holes 21.
- the metal material 22 constituting the domain structure 2 contracts due to discharge, the metal material 22 that has expanded to fill the holes 21 included in the domain structure 2 contracts, and the holes 21 are substantially reduced. The original size is restored.
- the holes 21 included in the domain structure 2 exhibit a buffering action when the metal material 22 expands or contracts, and relieve internal stress generated in the domain structure 2.
- the hole diameter of the air holes 21 is exemplified by about 0.05 to 5 ⁇ m, but is not particularly limited.
- the volume of the pores 21 occupying the deposition of the domain structure 2, that is, the porosity, may be appropriately determined in consideration of the mechanical strength of the domain structure 2 and the required degree of internal stress relaxation effect.
- the porosity is preferably 10 to 98%, more preferably 50 to 80%.
- the domain structure 2 is arranged so that a plurality of domain structures 2 are separated from each other.
- the domain structure 2 has the pores 21 therein, thereby relieving stress generated therein.
- the domain structures 2 are connected to each other, that is, when the electrode is provided as a single plate-like porous body without having a domain structure, the height direction of the electrode.
- the stress in the lateral direction may cause a crack in the electrode or may cause separation between the electrode and the current collector. Therefore, the domain structure 2 of the present embodiment is arranged such that the plurality of domain structures 2 are separated from each other. Thereby, the stress to the horizontal direction of the domain structure 2 at the time of charging / discharging is relieved, and generation
- the domain structure 2 has a polygonal shape that does not have an acute angle when viewed from above the current collector, and is formed so that the maximum diameter of the polygonal shape is 120 ⁇ m or less. That is, the domain structure 2 is formed so that the maximum diameter in a plan view is 120 ⁇ m or less.
- the present inventors When investigating the shape of an electrode, the present inventors have manufactured a porous electrode that is integrally formed and does not have a domain structure, and has studied how to generate cracks during charging and discharging. As a result, the present inventors have found that by repeating charge and discharge, the integral porous electrode is divided into a size of about 50 to 60 ⁇ m by cracks, and the maximum electrode diameter in plan view is 120 ⁇ m or less.
- the electrode is divided into a plurality of domain structures 2 and the maximum diameter when the domain structure 2 is viewed in plan is 120 ⁇ m or less.
- the maximum diameter when the domain structure 2 is viewed in plan is more preferably 100 ⁇ m or less, and further preferably 50 ⁇ m or less.
- the “maximum diameter when the domain structure 2 is viewed in plan” refers to a polygonal shape observed when the domain structure 2 is viewed in plan, passing through the center of the polygonal shape and passing through the polygonal shape. This means the maximum length of the dividing line that divides into two.
- the separation width x in each domain structure 2 is preferably 10 to 100 ⁇ m, more preferably 10 to 50 ⁇ m, and even more preferably 10 to 20 ⁇ m.
- all the separation widths in each domain structure 2 are the same for the reason described later, they are not necessarily the same.
- the domain structures 2 are arranged on the surface of the current collector 3 so as to be separated from each other.
- the electrode should be produced by spreading the domain structure on the surface of the current collector without any gaps. That's fine.
- the electrodes are spread over the surface of the current collector without any gaps, as described above, there is a risk that cracks will occur in the electrodes, or peeling between the electrodes and the current collector may occur.
- the domain structures 2 are separated from each other and the area of the current collector 3 where no electrode is provided is as much as possible. It is necessary to reduce it.
- the planar structure of the domain structure 2 is a rectangle, a square, or a regular hexagon.
- FIG. 4A to 4D are diagrams for explaining the arrangement state of each domain structure in the case where domain structures having various shapes in plan view are manufactured.
- FIGS. 4C and 4D when the planar view shape of the domain structure is a square or a regular hexagon, each domain structure is configured such that all the separation widths of the domain structures are equal to c or d. Can be arranged. At this time, by bringing c or d close to 0, the area occupancy of all domain structures on the current collector surface can be close to 100%. This applies similarly when the shape of the domain structure in plan view is rectangular. In this way, if the shape of the domain structure in plan view is rectangular, square or regular hexagonal, the area occupancy of the domain structure on the current collector surface can be freely designed while ensuring the necessary separation width. It is possible to design a large electrode.
- This lithium ion secondary battery includes the electrode 1 already described, the electrolyte described below, an electrode having a polarity opposite to that of the electrode 1, a separator, a gasket, a current collector, a sealing plate as other battery components, It is configured by appropriately combining cell cases and the like.
- the shape of the lithium ion secondary battery is not particularly limited, such as a cylindrical shape, a square shape, or a coin shape.
- the structure of the lithium ion secondary battery to be produced is not particularly limited. Basically, the negative electrode is placed on the cell floor plate, and the electrolyte and separator are further opposed to the negative electrode. In this way, a secondary battery is obtained by placing a positive electrode and caulking together with a gasket and a sealing plate.
- Solvents used in the electrolyte include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, ⁇ -butyl lactone, tetrahydrofuran, 2-methyltetrahydrofuran, sulfolane, 1,3 -Organic solvents such as dioxolane may be used singly or as a mixture of two or more.
- An electrolyte such as LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 or the like of about 0.5 to 2.0 M may be dissolved in these solvents.
- the materials that can be used as the positive electrode or the negative electrode described above can be used. These materials may be used by applying to a current collector.
- the electrode 1 of this embodiment may be used as one of the positive electrode or negative electrode of a lithium ion secondary battery, and the electrode 1 of this embodiment may be used as a positive electrode and a negative electrode.
- a material that is generally excellent in liquid retention may be used.
- a polyolefin resin nonwoven fabric or a porous film may be used. These functions can be expressed by impregnating the above-described electrolytic solution.
- 5A to 5F are perspective views sequentially illustrating an example of a manufacturing procedure in the electrode of this embodiment.
- 5A to 5F show an enlarged view of one domain structure 2 out of the electrodes 1 that are a set of a plurality of domain structures 2 in order to facilitate understanding.
- FIG. Moreover, although one embodiment of the manufacturing method described below is an explanation of a domain structure 2 having a regular hexagonal shape in plan view, the shape in plan view of the electrode 1 of the present invention is not limited thereto. Further, items that are the same as those described in the above-described electrode 1 are denoted by the same reference numerals and description thereof is omitted.
- the manufacturing method of this embodiment includes a resist layer forming step, a patterning step, a template introducing step, a metal material embedding step, and a template removing step.
- a resist layer forming step a patterning step
- a template introducing step a metal material embedding step
- a template removing step a metal material embedding step
- resist layer forming step In the manufacturing method of this embodiment, in order to produce the domain structure 2 to have a desired shape, a template produced using a resist composition is used. This step is a step of forming a resist layer 5 by applying a resist composition to the surface of the current collector 3 as shown in FIGS.
- the resist composition used may be negative or positive.
- a negative type resist composition is originally soluble in a developing solution, but has a property of becoming insoluble in a developing solution upon irradiation with active energy rays such as ultraviolet rays and electron beams.
- a positive type resist composition is originally insoluble in a developer, but has a property of being soluble in a developer upon irradiation with active energy rays such as ultraviolet rays and electron beams.
- the resist composition is not particularly limited, and known resist compositions can be used.
- a cationic polymerization resist composition containing a compound having an epoxy group and a cationic polymerization initiator
- Examples thereof include a system resist composition, (4) a monomer and / or resin having an ethylenically unsaturated bond, and a radical polymerization resist composition containing a radical polymerization initiator.
- (1) and (4) are negative type resist compositions
- (2) and (3) are positive type resist compositions.
- a known method can be used without any particular limitation.
- a guide hole 51 serving as a template for forming the domain structure 2 is formed in the resist layer 5.
- the guide hole 51 needs to be formed to have a depth sufficient to form the domain structure 2 having a desired height. Since the thickness of the resist layer 5 will be the depth of the guide hole 51 in the future, it is appropriately determined in consideration of the required depth of the guide hole 51.
- the thickness of the resist layer 5 is exemplified by 18 to 50 ⁇ m, but is not particularly limited.
- a patterning process is a process performed after the said resist layer formation process, and is a process shown by FIG.5 (C).
- a guide hole 51 having the same shape as seen in a plan view is formed in the resist layer 5 formed in the resist layer forming step.
- the guide hole 51 is formed as a through hole that penetrates the resist layer 5 to the surface of the current collector 3.
- the resist layer 5 formed in the resist layer forming step is selectively exposed through a mask having the same shape as the domain structure 2 to be manufactured in plan view.
- the resist layer 5 is formed of a negative resist composition
- the portion that will not become the guide hole 51 in the future is cured and becomes insoluble in the developer, and the portion that will become the guide hole 51 in the future becomes the developer. It remains soluble to it.
- the resist layer 5 is formed of a positive resist composition, the portion that will become the guide hole 51 in the future becomes soluble in the developer, and the portion that will not become the guide hole 51 in the future is in the developer. And remains insoluble.
- the resist layer 5 that has undergone selective exposure is developed. Development can be performed by a known method using a known developer. Examples of such a developer include an alkaline aqueous solution. Examples of the developing method include an immersion method and a spray method.
- the developed resist layer 5 is formed with a guide hole 51 having the same shape as the domain structure 2 to be produced in plan view and penetrating to the surface of the current collector 3.
- the resist layer 5 in which the guide holes 51 are formed is subjected to after-curing that irradiates active energy rays such as ultraviolet rays or post-baking, which is an additional heat treatment, as necessary.
- a template introduction process is a process performed after the said patterning process, and is a process shown by FIG.5 (D).
- polymer fine particles 6 such as polystyrene and PMMA (polymethyl methacrylate) are deposited on the surface of the current collector 3 existing at the bottom of the guide hole 51 formed in the patterning step. These polymer fine particles 6 are used for forming the pores 21 in the domain structure 2. That is, after depositing the polymer fine particles 6 in this step, the metal material 22 as the electrode material is buried in the guide hole 51 in the metal material embedding step described later, and further, the polymer fine particles in the template removing step described later. By removing 6, holes 21 are formed. That is, the polymer fine particle 6 is a template for forming the pores 21 in the domain structure 2.
- the material of the polymer fine particles 6 is not particularly limited as long as it can be removed by a solvent, heat treatment, or the like in a template removal step described later, and examples thereof include polystyrene and PMMA.
- the shape of the polymer fine particles 6 is not particularly limited, but is preferably spherical. It is preferable that the polymer fine particles 6 have a spherical shape, so that the polymer fine particles 6 can be filled in the inside of the guide hole 51 in a close-packed manner.
- Examples of the particle diameter of the polymer fine particles 6 include 0.05 to 5 ⁇ m.
- the pore diameter of the pores 21 in the domain structure 2 can be adjusted by the particle diameter of the polymer fine particles 6 to be used.
- electrophoresis As a method for depositing the polymer fine particles 6 in the guide hole 51, electrophoresis can be used.
- the current collector 3 exposed at the bottom of the guide hole 51 is used as an electrode for electrophoresis, and the current collector 3 and the counter electrode with respect to the current collector 3 are in a liquid in which the polymer fine particles 6 are suspended. And an electric field for depositing the polymer fine particles 6 on the surface of the current collector 3 may be applied thereto.
- a method of depositing the polymer fine particles 6 by supplying a liquid in which the polymer fine particles 6 are suspended to the inside of the guide hole 51 and then drying the liquid contained in the supplied suspension, or centrifugal separation A method of depositing the polymer fine particles 6 inside the guide holes 51 by a method may be employed.
- the thickness at which the polymer fine particles 6 are deposited inside the guide hole 51 may be appropriately determined in consideration of the height of the domain structure 2 to be formed.
- the depth of the guide hole 51 that is, the height of the resist layer 5 is determined in consideration of the height of the domain structure 2 to be produced. However, it is not particularly limited.
- the liquid used in the electrophoresis is charged on the surface of the polymer fine particles 6 such as an amidine compound or a sulfate ester compound. It is preferable to add a compound that gives.
- the polymer fine particles 6 are deposited inside the guide holes 51, it is preferable to fuse the particles of the polymer fine particles 6 by performing a heat treatment at about 80 to 120 ° C. By performing this heat treatment, the polymer fine particles 6 can be maintained in a fixed state in a metal material embedding step described later. In the metal material embedding step, the fine polymer particles 6 maintain a regular arrangement inside the guide holes 51, whereby the holes 21 in the finally obtained domain structure 2 are also regularly arranged.
- the metal material embedding step is a step performed after the template introduction step, and is a step shown in FIG. In this step, the metal material 22 for forming the positive electrode or the negative electrode is filled in the guide hole 51 where the polymer fine particles 6 are deposited.
- the metal material 22 to be filled in the guide hole 51 is appropriately selected according to whether the domain structure 2 to be produced constitutes a positive electrode or a negative electrode. Since the metal material for constituting the positive electrode and the metal material for constituting the negative electrode have already been described, the description thereof is omitted here.
- a plating method in which the metal material 22 is electrically deposited on the surface of the current collector plate 3 using a known plating solution, or fine particles of the metal material 22 are suspended. Electrophoresis in which the metal material 22 is deposited on the surface of the current collector plate 3 by electrophoresis using a turbid liquid, and a liquid in which fine particles of the metal material 22 are suspended is directly injected into the guide hole 51 by a capillary. Then, an injection method of drying and then drying is exemplified. These methods can be appropriately selected according to the type of the metal material 22 filled in the guide hole 51.
- the polymer fine particles 6 deposited in the guide holes 51 in the template introduction process are embedded in the metal material 22 through the metal material embedding process. Thereby, in the guide hole 51, the metal material 22 does not exist in the place where the polymer fine particles 6 exist, and the metal material 22 exists only in the place where the polymer fine particles 6 do not exist.
- the template removal step is a step performed after the metal material embedding step and is a step shown in FIG. In this step, the polymer fine particles 6 embedded in the metal material 22 are removed. Thereby, the location where the polymer fine particles 6 existed becomes a space, and the pores 21 are formed.
- the domain structure 2 being formed may be immersed in a solvent that can dissolve the polymer fine particles 6.
- a solvent is appropriately selected according to the type of the polymer fine particles 6. Examples thereof include toluene, acetone, ethyl acetate, limonene, methanol, ethanol, isopropyl alcohol, acetonitrile, and the like.
- the time for immersing the domain structure 6 being formed in the solvent may be appropriately determined according to the dissolution state of the polymer fine particles 6, but an example is about 24 hours.
- the domain structure 2 being formed is taken out of the solvent, rinsed with a solvent such as acetone, and then vacuum-dried, whereby the domain structure 2 constituting the electrode 1 is obtained. Complete.
- an ashing method in which heating is performed at a high temperature may be used.
- the domain structure 2 is formed through the above steps.
- the manufacturing method has been described by focusing on one domain structure 2.
- the electrode 1 is an aggregate of a plurality of domain structures 2, in practice, A plurality of domain structures 2 are formed on the surface of the current collector 3.
- the plurality of domain structures 2 may be formed on the surface of the current collector 3 at the same time, or one or several of them may be sequentially formed on the surface of the current collector 3 by repeating the above steps. .
- a plurality of domain structures 2 are simultaneously formed on the surface of the current collector 3, a plurality of figures having the same shape as the plan view shape of the domain structures 2 are formed through a predetermined separation distance in the pattern forming step.
- the resist layer 5 may be selectively exposed using a mask.
- the domain structure 2 formed through these steps is surrounded by a resist layer 5.
- the domain structure 2 may be used as an electrode in this state, or may be used as an electrode after removing the resist layer 5 existing around if necessary.
- Examples of a method for removing the resist layer 5 present around the domain structure 2 include known methods, and examples thereof include an ashing method and an etching method in which the resist layer 5 is decomposed by heating at a high temperature.
- the domain structure 2 formed as a polygonal column shape is exposed on the surface of the current collector 3 as shown in FIG.
- FIG. 5 is a plan view showing a second embodiment of the electrode of the present invention.
- the electrode 1 of the first embodiment described above was formed as an aggregate of domain structures 2 having the same polarity on the surface of a single current collector 3. That is, the electrode 1 of 1st Embodiment is formed as either a positive electrode or a negative electrode on the same plane.
- the strip-like positive electrode current collector 3a and the negative electrode current collector 3b are alternately provided on the surface of one base material 4, and the positive electrode current collector 3a has a positive electrode on the surface.
- a certain electrode 1a is formed on the surface of the negative electrode current collector 3b.
- both the positive electrode 1a and the negative electrode 1b are alternately formed on the same plane.
- the number of times that the positive electrode 1a and the negative electrode 1b are alternately repeated is one or more times, and is not particularly limited. Further, the number of the positive electrodes 1a and the negative electrodes 1b formed on the surface of the substrate 4 is not necessarily the same.
- the positive electrode 1a is formed as a group of positive electrode domain structures 2a arranged in a line on the surface of the positive electrode current collector 3a.
- the negative electrode 2b is formed as a group of negative electrode domain structures 2b arranged in a line on the surface of the negative electrode current collector 3b.
- the structure and formation method of the positive electrode domain structure 2a and the negative electrode domain structure 2b are the same as those of the domain structure 2 already described.
- the planar view shapes of the positive electrode domain structure 2a and the negative electrode domain structure 2b are represented by regular hexagons, but the planar view shapes of the positive electrode domain structure 2a and the negative electrode domain structure 2b are regular hexagons. It is not limited to.
- the positive electrode current collector 3 a and the negative electrode current collector 3 b have a strip shape and are alternately provided on the surface of the substrate 4.
- Such a positive electrode current collector 3a and a negative electrode current collector 3b are formed, for example, by forming the current collectors 3a and 3b as opposing comb-shaped metal foils, and combining these with each comb-shaped tooth portion. And may be arranged so as to be combined with each other.
- the electrodes 3a and 3b are provided on the comb-shaped teeth, and positive and negative currents are extracted from the comb-shaped peaks.
- the positive electrode current collector 3a and the negative electrode current collector 3b are arranged apart from each other.
- the thing similar to the collector 3 already demonstrated can be used.
- a method of forming the positive electrode current collector 3a and the negative electrode current collector 3b a method of laminating a metal foil on the surface of the substrate 4 and processing the metal foil into a desired shape by a known method is exemplified.
- the shapes of the positive electrode domain structure 2a and the negative electrode domain structure 2b (hereinafter also referred to as “domain structures 2a and 2b”) in the present embodiment are not particularly limited, but the shape in plan view is rectangular as in the first embodiment. It is preferable to provide a square or a regular hexagon. The reason for this is as follows, in addition to the one described in the first embodiment.
- the separation distance between the domain structures 2a and 2b can be made uniform.
- the positive electrode domain structure 2a and the negative electrode domain structure 2b are alternately arranged in the direction perpendicular to the length direction of the current collectors 3a and 3b (that is, the horizontal direction in FIG. 5). Therefore, if the separation distance between the domain structures 2a and 2b is uniform, the positive electrode domain structure 2a and the negative electrode domain structure 2b are arranged at a uniform separation distance from each other.
- the separation distances of the current collectors 3a and 3b are preferably the same.
- the substrate 4 Since the positive electrode current collector 3a and the negative electrode current collector 3b are provided on the surface of the substrate 4, it is desirable that the substrate 4 has an insulating surface from the viewpoint of preventing them from short-circuiting.
- a substrate 4 is not particularly limited, but a silicon substrate having an oxide film on the surface is exemplified.
- the arrangement of the domain structures 2a and 2b is such that only the negative electrode domain structure 2b exists around one positive electrode domain structure 2a and one negative electrode domain structure 2b Only the positive electrode domain structure 2a may exist around. That is, in the second embodiment, the polarities of the domain structures adjacent in the horizontal direction in FIG. 5 (the direction perpendicular to the length direction of the current collectors 3a and 3b) are opposite, while the vertical direction in FIG. Although the polarities of the domain structures adjacent to each other (the length direction of the current collectors 3a and 3b) are the same, in this modification, the polarities of the domain structures adjacent not only in the horizontal direction but also in the vertical direction in FIG. The opposite is true. In this case, the positive electrode current collector and the negative electrode current collector are appropriately arranged so as not to short-circuit each other.
- each of the domain structures 2, 2 a, and 2 b has a regular hexagonal shape in plan view, but is not limited thereto, and may be a polygonal shape that does not have an acute angle in plan view.
- the electrode 1, 1a, 1b was an electrode for lithium ion secondary batteries, it is not limited to this, It uses preferably in the secondary battery with an expansion and contraction of an electrode at the time of charging / discharging. can do.
- Such secondary batteries include secondary batteries that involve release of metal ions from the material constituting the electrode and occlusion of metal into the material constituting the electrode, as well as lead-acid batteries, nickel cadmium batteries, nickel metal hydride batteries, etc.
- General secondary batteries such as
- This resist composition is a novolak type and is a positive type.
- Example 1 Cu foil or film for each of a flexible substrate (thickness 50 ⁇ m) which is a Cu foil and a hard substrate (substrate having a 5000 ⁇ m thick Cu sputtered film formed on the surface of a 750 ⁇ m thick silicon wafer).
- the above resist composition was applied to the surface provided with, and the solvent contained in the resist composition was evaporated to form a resist layer having a thickness of 20 ⁇ m.
- the resist layer was irradiated with ultraviolet rays (ghi mixed line, 3000 mJ / cm 2 ) through a photomask, developed with an alkaline developer, and washed with pure water.
- a plurality of through holes (guide holes) having a regular hexagonal shape with a side of 50 ⁇ m and penetrating to the surface of the Cu foil or film were formed in a honeycomb shape on the surface of the Cu foil or film.
- all the separation widths of adjacent through holes were set to 15 ⁇ m.
- monodispersed spherical particles of polystyrene (diameter 1 ⁇ m, hereinafter referred to as “polystyrene particles”) are dispersed in 2-propanol (80 mL) at a concentration of 0.43% by mass to prepare a suspension.
- the working electrode cathode
- Ni plate 3 cm x 4 cm, thickness 0.3 mm
- the counter electrode anode
- the distance between the electrodes is 1 cm and 600 V
- polystyrene particles were deposited in each of the plurality of through holes.
- the polystyrene particles deposited in the through-holes were heat-fused by heating the whole substrate at a temperature of 110 ° C. for 15 minutes.
- NiCl 2 ⁇ 6H 2 0 is 0.075 mol / L
- SnCl 2 ⁇ 2H 2 O is 0.175 mol / L
- K 2 P 2 O 7 is 0.50 mol / L
- NH 2 CH 2 COOH was added to a concentration of 0.125 mol / L
- 28% aqueous ammonia was added to adjust the pH of the aqueous solution to 8.5.
- the obtained aqueous solution was used as a Sn—Ni plating bath, and an electrolytic plating process was performed using a Cu foil or film partially exposed through the through-hole as a working electrode (cathode) and a Sn plate as a counter electrode (anode).
- the electrolytic plating treatment was performed by applying a constant current of 1.75 mA for 1.5 hours.
- the substrate after the electrolytic plating treatment was immersed in toluene for 24 hours and then washed with acetone to remove the polystyrene particles deposited in the through-holes, and further vacuum drying was performed.
- an electrode having a plurality of domain structures made of a porous Sn—Ni alloy was formed on each of the flexible substrate and the hard substrate. This electrode was used as the electrode of Example 1.
- the thickness of the formed electrode was 10 ⁇ m for both the flexible substrate and the hard substrate.
- Example 2 The shape of the through holes formed in the resist layer is a square with a side of 50 ⁇ m, and the through holes are separated into tiles that are straight lines that do not block all joints, with the spacing between adjacent through holes being 15 ⁇ m.
- the electrode of Example 2 was formed in the same procedure as in Example 1 except that the electrodes were placed and the energization time of the electrolytic plating treatment was 1 hour.
- the domain structure in the electrode of a present Example is arrangement
- the shape of the through holes formed in the resist layer is a circle having a diameter of 18 ⁇ m, and the through holes are arranged in a staggered manner with the lateral and vertical spacing widths between the through holes being 17 ⁇ m.
- the electrode of Comparative Example 1 was formed in the same procedure as Example 1 except that the constant current was 1.37 mA and the energization time was 0.9 hours. The thickness of the formed electrode was 20 ⁇ m for both the flexible substrate and the hard substrate.
- the electrode mass per unit area in the electrode forming portion was measured.
- the electrode of Example 1 was 4.5 to 5.0 mg / cm 2 .
- the electrode of No. 2 was 4.0 to 4.5 mg / cm 2
- the electrode of Comparative Example 1 was 2.2 to 2.6 mg / cm 2 . From this, it can be seen that the electrode of the present invention has a larger mass than an electrode having a domain structure of a round shape in plan view and has more electrode material.
- Each of the electrodes of Examples 1 and 2 and Comparative Example 1 provided on the flexible substrate was opposed to metallic lithium via a separator, and an electrolytic solution (1 mol / L LiClO 4 was dissolved between the electrode and metallic lithium.
- metallic lithium serves as a counter electrode and a reference electrode, and the negative electrode characteristics of the electrodes of Example 1, Example 2, or Comparative Example 1, which are working electrodes, are evaluated.
- the discharge capacity when charging and discharging were repeated 1 to 4 cycles was measured based on the two-electrode electrochemical measurement.
- the electrodes of Examples 1 and 2 exhibit a larger discharge capacity than the electrode of Comparative Example 1. From this, the effectiveness of the present invention is understood. Further, as shown in FIG. 8, it is understood that among the electrodes of the present invention, the electrode of Example 1 has a smaller decrease in the discharge capacity when charging and discharging are repeated than the electrode of Example 2. From this, it is understood that the shape of the domain structure constituting the electrode is preferably a regular hexagon in terms of obtaining good charge / discharge cycle characteristics.
- the discharge capacity when charge / discharge was repeated for 1 to 100 cycles based on the two-electrode electrochemical measurement. was measured.
- metallic lithium serves as a counter electrode and a reference electrode, and the negative electrode characteristics of the electrode of Example 1 which is a working electrode are evaluated.
- the produced electrochemical measurement cell was measured for discharge capacity when charging and discharging were repeated 1 to 100 cycles based on two-electrode electrochemical measurement.
- the measurement of discharge characteristics manufactured by Hokuto Denko Corporation, using HSV-100 Model instrument, the potential range as 0 ⁇ 2.5V, current to 0V at a current density 0.1MAcm -2 after constant current charging
- the battery was charged at a constant potential at 0 V until the density became 0.01 mAcm ⁇ 2 or less. Thereafter, constant current discharge was performed to 2.5 V at a current density of 0.1 mAcm ⁇ 2 .
- FIG. 9 shows a plot showing the transition of the discharge capacity with respect to the number of cycles for the results of this cycle test. For reference, FIG. 9 shows the discharge capacity (360 mAhg ⁇ 1 ) when a general graphite electrode is used as the negative electrode.
- the electrode of Example 1 maintains a high discharge capacity even when the charge / discharge cycle reaches 100 cycles. From this, it can be seen that by applying the present invention, the life of the alloy-based negative electrode, which has hitherto been difficult to achieve a long life with a high capacity, can be greatly improved.
- Example 1 a lithium ion secondary battery in which the electrode of Example 1 was used as a negative electrode and a LiNi 0.8 Co 0.15 Al 0.05 O 2 electrode serving as a positive electrode of the lithium ion secondary battery was combined with the negative electrode was used.
- the electrode of Example 1 was cut into a size of 28 mm ⁇ 68 mm to produce a negative electrode.
- Laminating uses a commercial desktop sealed packaging machine (manufactured by Sharp Corporation, sold by Asahi Kasei Packs Co., Ltd., trade name SQ-303), with a junction temperature of about 180 ° C., intake performance of 66.7 kPa, and intake time. It was carried out as 10 seconds.
- FIG. 10 shows a plot of the charge / discharge characteristics observed at that time.
- the charging conditions were a potential range of 2 to 4.3 V, and constant potential charging at 4.3 V until the current density became 0.5 mAcm ⁇ 2 or less after constant current charging to 4.3 V at a current density of 4 mAcm ⁇ 2 . . Thereafter, constant current discharge was performed up to 2 V at a current density of 4 mAcm ⁇ 2 .
- the produced lithium ion secondary battery had charge / discharge characteristics, and it was shown that the electrode of the present invention is useful for producing a secondary battery.
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Abstract
Description
従来、例えば、リチウムイオン二次電池のように、電極からのイオンの放出又は電極へのイオンの吸蔵を伴う二次電池において電極を合金等の金属材料で形成させると、その電極は、充放電の際に、合金化及び脱合金化に伴う体積変化により大きな内部応力を発生させ、この内部応力により微粉化してその後の充放電容量を減少させる。本発明者らは、このような体積変化に伴う内部応力が、従来の二次電池における電極が箔状や板状等といった隙間のない一塊の構造として形成されていたことに伴って生じていたことを見出し、電極1を互いに離間した複数の多孔質ドメイン構造2の集合として形成させればこれらの問題を解決できることを知見した。
本実施態様の製造方法では、ドメイン構造2を所望の形状となるように作製するために、レジスト組成物を使用して作製した鋳型を使用する。この工程は、図5(A)から(B)に示すように、集電体3の表面にレジスト組成物を塗布してレジスト層5を形成させる工程である。
次に、パターニング工程について説明する。パターニング工程は、上記レジスト層形成工程の後に行われる工程であり、図5(C)で示される工程である。この工程では、上記レジスト層形成工程で形成されたレジスト層5に、作製しようとするドメイン構造2と平面視で同一形状となる形状のガイド孔51を形成させる。ガイド孔51は、集電体3の表面までレジスト層5を貫通する貫通孔として形成される。
次に、テンプレート導入工程について説明する。テンプレート導入工程は、上記パターニング工程の後に行われる工程であり、図5(D)で示される工程である。この工程では、上記パターニング工程で形成されたガイド孔51の底部に存在する集電体3の表面に、ポリスチレンやPMMA(ポリメチルメタクリレート)等の高分子微粒子6を堆積させる。これらの高分子微粒子6は、ドメイン構造2における空孔21を形成させるために使用される。つまり、本工程で高分子微粒子6を堆積させた後、後述する金属材料埋め込み工程にて、ガイド孔51に電極材料である金属材料22を埋め込み、さらに、後述するテンプレート除去工程にて高分子微粒子6を取り除くことにより、空孔21が形成される。すなわち、高分子微粒子6は、ドメイン構造2における空孔21を形成させるための鋳型である。
なお、高分子微粒子6をガイド孔51の内部に堆積させる手段として電気泳動を使用する場合、当該電気泳動において使用する液体に、アミジン化合物や硫酸エステル化合物のような高分子微粒子6の表面に電荷を与える化合物を添加しておくことが好ましい。
次に、金属材料埋め込み工程について説明する。金属材料埋め込み工程は、上記テンプレート導入工程の後に行われる工程であり、図5(E)で示される工程である。この工程では、高分子微粒子6が堆積されたガイド孔51の内部に、正極又は負極を形成させる金属材料22を充填させる。
次に、テンプレート除去工程について説明する。テンプレート除去工程は、上記金属材料埋め込み工程の後に行われる工程であり、図5(F)で示される工程である。この工程では、金属材料22に埋まっている高分子微粒子6を除去する。これにより、高分子微粒子6の存在していた箇所が空間となり、空孔21が形成される。
クレゾール型ノボラック樹脂(m-クレゾール:p-クレゾール=6:4(質量比)、質量平均分子量30000)70質量部と、感光剤として1,4-ビス(4-ヒドロキシフェニルイソプロピリデニル)ベンゼンのナフトキノン-1,2-ジアジド-5-スルホン酸時エステル15質量部と、可塑剤としてポリメチルビニルエーテル(質量平均分子量100000)15質量部とに対して、溶剤としてプロピレングリコールモノメチルエーテルアセテート(PGMEA)を固形分濃度が40質量%になるように添加してから、混合して溶解させ、レジスト組成物を調製した。このレジスト組成物は、ノボラック系であり、ポジ型である。
Cu箔であるフレキシブル基板(厚さ50μm)、及びCu膜を表面に有するハード基板(厚さ750μmのシリコンウェーハの表面に5000ÅのCuスパッタ膜を形成させた基板)のそれぞれについて、Cu箔又は膜が設けられた表面に上記レジスト組成物を塗布し、レジスト組成物に含まれていた溶剤を蒸発させ、厚さ20μmのレジスト層を形成させた。このレジスト層にフォトマスクを通して、紫外線(ghi混合線、3000mJ/cm2)を照射し、次いでアルカリ現像液で現像し、純水で洗浄した。これにより、Cu箔又は膜の表面に、1辺が50μmの正六角形であり、Cu箔又は膜の表面まで貫通する複数の貫通孔(ガイド孔)をハニカム状に形成させた。なお、隣接する貫通孔同士の全ての離間幅を15μmとした。
次に、ポリスチレンの単分散球状粒子(直径1μm、以下「ポリスチレン粒子」と呼ぶ。)を0.43質量%の濃度で2-プロパノール(80mL)に分散させ、懸濁液を調製し、この懸濁液中で、貫通孔により一部が露出したCu箔又は膜を作用極(陰極)、Ni板(3cm×4cm、厚さ0.3mm)を対極(陽極)として電極間距離を1cmとし600Vの電圧を印加し、1分間電気泳動を行った。この操作により、複数の貫通孔のそれぞれにポリスチレン粒子を堆積させた。その後、基板ごと110℃の温度にて15分間加熱することにより、貫通孔の中に堆積しているポリスチレン粒子同士を熱融着させた。
次に、蒸留水に、NiCl2・6H20を0.075mol/L、SnCl2・2H2Oを0.175mol/L、K2P2O7を0.50mol/L、及びNH2CH2COOHを0.125mol/Lの濃度になるようにそれぞれ添加し、さらにこの水溶液のpHが8.5になるように28%アンモニア水を添加した。得られた水溶液をSn-Niめっき浴として使用し、貫通孔により一部が露出したCu箔又は膜を作用極(陰極)、Sn板を対極(陽極)として、電解めっき処理を行った。電解めっき処理は、1.75mAの定電流を1.5時間通電させて行った。
電解めっき処理を経た基板をトルエンに24時間浸漬させてからアセトンで洗浄することにより、貫通孔に堆積したポリスチレン粒子を除去し、さらに真空乾燥を行った。これらの手順を経て、多孔質のSn-Ni合金からなるドメイン構造を複数有する電極を、フレキシブル基板及びハード基板のそれぞれについて形成させた。この電極を実施例1の電極とした。なお、形成させた電極の厚さは、フレキシブル基板及びハード基板のいずれの場合も10μmだった。
レジスト層に形成させた貫通孔の形状を1辺が50μmの正方形とし、この貫通孔を、隣接する貫通孔同士の離間幅を全て15μmとして、全ての目地が遮られない直線となるタイル状に配置し、かつ電解メッキ処理の通電時間を1時間にしたこと以外は、実施例1と同様の手順にて実施例2の電極を形成させた。なお、本実施例の電極におけるドメイン構造は、平面視で、図4(C)に示すような配置である。また、形成させた電極の厚さは、フレキシブル基板及びハード基板のいずれの場合も20μmだった。
レジスト層に形成させた貫通孔の形状を直径が18μmの円とし、この貫通孔を、貫通孔同士の横方向及び縦方向の離間幅が全て17μmとして、千鳥状に配置し、かつ電解メッキ処理における定電流を1.37mAとし、通電時間を0.9時間としたこと以外は、実施例1と同様の手順にて比較例1の電極を形成させた。なお、形成させた電極の厚さは、フレキシブル基板及びハード基板のいずれの場合も20μmだった。
また、図8に示すように、本発明の電極の中でも、実施例1の電極は、充放電を繰り返した際の放電容量の低下が実施例2の電極よりも小さいことが理解される。このことから、良好な充放電サイクル特性を得るとの観点において、電極を構成するドメイン構造の平面視形状が正六角形であることが好ましいと理解される。
2 ドメイン構造(多孔質ドメイン構造)
3 集電体
Claims (6)
- 集電体の表面に、互いに離間した複数の多孔質ドメイン構造の集合として形成され、
前記多孔質ドメイン構造が、平面視で鋭角を持たない多角形形状であり、かつ前記多角形形状の最大径が120μm以下である電極。 - 前記ドメイン構造の形状が平面視で長方形、正方形又は正六角形である請求項1記載の電極。
- 前記ドメイン構造は、各ドメイン構造の離間幅が一定となるように配置される請求項1又は2記載の電極。
- 二次電池用である請求項1~3のいずれか1項記載の電極。
- 前記二次電池がリチウムイオン二次電池である請求項4記載の電極。
- 請求項5記載の電極を使用してなるリチウムイオン二次電池。
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KR1020137004398A KR20130054997A (ko) | 2010-07-23 | 2011-06-22 | 2 차 전지용 다공질 전극 |
CN201180045450.7A CN103155230B (zh) | 2010-07-23 | 2011-06-22 | 二次电池用多孔电极 |
DE112011102465T DE112011102465T5 (de) | 2010-07-23 | 2011-06-22 | Poröse Elektrode für eine Sekundärbatterie |
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JP2011028752A JP5787307B2 (ja) | 2010-07-23 | 2011-02-14 | 二次電池用多孔質電極 |
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WO2013161733A1 (ja) * | 2012-04-24 | 2013-10-31 | 昭和電工株式会社 | リチウム二次電池用負極活物質およびその製造方法 |
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WO2016161587A1 (en) * | 2015-04-09 | 2016-10-13 | Kechuang Lin | Electrode material and energy storage apparatus |
FR3064116B1 (fr) * | 2017-03-15 | 2021-07-16 | Ecole Nat Superieure Des Mines | Accumulateur deformable |
US11201393B2 (en) | 2018-11-09 | 2021-12-14 | International Business Machines Corporation | Electrochemically controlled capillarity to dynamically connect portions of an electrical circuit |
CN111384360B (zh) | 2018-12-27 | 2022-02-22 | 财团法人工业技术研究院 | 金属离子电池 |
CN112820937B (zh) * | 2019-11-15 | 2022-05-17 | 郑州宇通集团有限公司 | 固体电解质及其制备方法、高镍三元全固态电池 |
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US20130209872A1 (en) | 2013-08-15 |
TWI517485B (zh) | 2016-01-11 |
KR20130054997A (ko) | 2013-05-27 |
JP5787307B2 (ja) | 2015-09-30 |
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DE112011102465T5 (de) | 2013-05-08 |
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