WO2023058557A1 - Secondary battery and method for producing same - Google Patents

Secondary battery and method for producing same Download PDF

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Publication number
WO2023058557A1
WO2023058557A1 PCT/JP2022/036505 JP2022036505W WO2023058557A1 WO 2023058557 A1 WO2023058557 A1 WO 2023058557A1 JP 2022036505 W JP2022036505 W JP 2022036505W WO 2023058557 A1 WO2023058557 A1 WO 2023058557A1
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Prior art keywords
semi
solid
electrode layer
secondary battery
electrode
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PCT/JP2022/036505
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French (fr)
Japanese (ja)
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真人 藤岡
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株式会社村田製作所
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Publication of WO2023058557A1 publication Critical patent/WO2023058557A1/en

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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
    • 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
    • H01M10/058—Construction or manufacture
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a secondary battery, particularly a secondary battery including a semi-solid electrode, and a manufacturing method thereof.
  • a secondary battery generally has a structure in which a laminate in which a positive electrode having a positive electrode layer and a negative electrode having a negative electrode layer are alternately laminated with separators interposed therebetween, and an electrolytic solution are accommodated in an exterior body.
  • electrodes such as the positive electrode and the negative electrode, binder-bonded electrodes are used in which an electrode active material, a conductive agent, and the like are bonded on a current collector with a binder.
  • a method for manufacturing a secondary battery including a binder-bonded electrode includes, as an electrode manufacturing step, a preparation step of preparing an electrode layer-forming coating solution; coating a current collector with an electrode layer-forming coating solution; A coating step; a drying step for drying the coated electrode layer; a pressing step for consolidating the electrode precursor; a slitting step for cutting the electrode precursor into a desired width; a cutting step to form; an assembling step, a welding step of connecting tabs to the electrodes; A lamination step of producing; a liquid injection step of sandwiching the produced laminate in an outer package and injecting an electrolytic solution into the outer package; a vacuum impregnation step of impregnating an electrode with an electrolytic solution while holding the outer package in a vacuum; An encapsulation step of enclosing in an outer package; a charging and discharging step of forming a solid electrolyte interfacial coating on the surface of the negative electrode active material by an initial charging treatment to form a secondary battery precursor; and an aging step
  • Semi-solid electrodes can be made significantly thicker than conventional electrodes, so the ratio of active to inactive materials (i.e., current collectors and separators) is second to none using conventional electrodes. Compared to batteries, batteries using semi-solid electrodes can be expensive. This greatly increases the overall charge capacity and energy density of secondary batteries containing semi-solid electrodes. However, in a secondary battery including a semi-solid electrode, since the semi-solid electrode does not undergo a pressing process, the electrode layer and the current collector are not sufficiently crimped, and the interfacial resistance between the electrode layer and the current collector increases. easy. As a result, rate characteristics deteriorated.
  • the conductive aid has a high liquid trapping property, the amount of electrolytic solution required to impart fluidity to the electrode increases. As a result, the energy density decreased.
  • An object of the present invention is to provide a secondary battery with more excellent rate characteristics and sufficiently superior energy density, and a method for manufacturing the same.
  • the energy density is, for example, a characteristic related to the amount of energy that can be generated from one electrode layer, and specifically, it may be a characteristic determined according to the content ratio of the active material in the semi-solid electrode layer.
  • the rate characteristics are, for example, the capacity retention rate of a secondary battery when discharged at a high rate (for example, characteristics relating to discharge capacity at a high rate/discharge capacity at a standard rate).
  • Another object of the present invention is to provide a secondary battery that has superior rate characteristics, sufficiently superior energy density, and that can be manufactured with fewer manufacturing steps, and a method for manufacturing the same.
  • the present invention A semi-solid electrode having a semi-solid electrode layer containing an electrode active material, a conductive aid and an electrolytic solution, and a current collector,
  • the semi-solid electrode relates to a secondary battery having a carbon layer between the semi-solid electrode layer and the current collector.
  • the present invention also provides A method for manufacturing the above secondary battery, which method includes the following steps: A preparation step of mixing an electrode active material, a conductive aid and an electrolytic solution to prepare an electrode layer slurry; Carbon layer forming step of forming a carbon layer on the current collector; A coating step of coating an electrode layer slurry on a current collector having a carbon layer to form an electrode; A lamination step of laminating and producing a laminate so that a separator is arranged between electrodes; An enclosing step of enclosing the laminate in the outer package.
  • the interfacial resistance between the electrode layer and the current collector can be reduced even if the electrode does not undergo a pressing process, so that the rate characteristics can be sufficiently improved.
  • the amount of the conductive agent added is the minimum amount necessary to ensure the conductivity of the electrode layer, so the amount of electrolytic solution for imparting fluidity to the electrode can be reduced. It is also possible to increase the energy density.
  • the manufacturing process of the secondary battery can be significantly simplified, so that equipment investment costs and manufacturing process costs can be greatly reduced.
  • the secondary battery of the present invention also has an increased energy density because the amount of electrolyte required to impart fluidity to the electrodes is reduced. Since the secondary battery of the present invention does not contain a binder and can achieve low resistance, it is sufficiently excellent in rate characteristics.
  • FIG. 1 is an example of a schematic cross-sectional view of a secondary battery according to one embodiment of the present invention, for explaining the mechanism by which the rate characteristics are improved in the secondary battery.
  • FIG. 2 is a schematic cross-sectional view of a conventional secondary battery for explaining the mechanism of deterioration of rate characteristics in the conventional secondary battery.
  • the present invention provides a secondary battery.
  • the term “secondary battery” refers to a battery that can be repeatedly charged and discharged.
  • “Secondary battery” is not overly bound by its name, and can include, for example, electrochemical devices such as "power storage device.”
  • the term “planar view” refers to a state (top view or bottom view) when an object is viewed from above or below (especially above) along the thickness direction (for example, the stacking direction of electrodes and separators). That is.
  • the term “cross-sectional view” as used herein refers to a cross-sectional state (cross-sectional view) when viewed from a direction perpendicular to the thickness direction.
  • each member constituting the secondary battery in the present invention is arranged on each of the positive electrode side and the negative electrode side.
  • electrodes include positive and negative electrodes.
  • an electrode active material (or active material) includes a positive electrode active material and a negative electrode active material.
  • the conductive aid includes a positive electrode conductive aid and a negative electrode conductive aid.
  • the electrolyte includes a positive electrolyte and a negative electrolyte. Electrolyte solutions having the same composition may be used for the positive electrode electrolyte solution and the negative electrode electrolyte solution.
  • a secondary battery 10 of the present invention has a semi-solid electrode 1 as shown in FIG.
  • the semi-solid electrode in FIG. 1 schematically shows one of a semi-solid positive electrode or a semi-solid negative electrode.
  • the semisolid electrode 1 has a semisolid electrode layer 7 , a current collector 5 , and a carbon layer 6 between the semisolid electrode layer 7 and the current collector 5 .
  • the semi-solid electrode layer 7 is a layer that normally contains the electrode active material 2, the conductive aid 3 and the electrolytic solution 4 and has fluidity.
  • FIG. 2 shows a conventional secondary battery having a semi-solid electrode 1'.
  • the semi-solid electrode 1' includes a semi-solid electrode layer 7' containing an active material 2', a conductive agent 3', and an electrolytic solution 4', and a current collector 5'.
  • the conventional secondary battery of FIG. 2 does not have carbon layer 6 .
  • the semi-solid electrodes 1 and 1' are also referred to as clay electrodes in that they comprise semi-solid electrode layers.
  • the conductive aid 3 does not necessarily have to be contained in both the semi-solid positive electrode and the semi-solid negative electrode.
  • both the positive electrode and the negative electrode may each contain the conductive aid 3, or neither of them may contain them.
  • the positive electrode may contain the conductive aid 3 and the negative electrode may not contain the conductive aid 3 .
  • FIG. 1 is a cross-sectional view schematically showing an example of the basic structure of a secondary battery according to one embodiment of the present invention.
  • both the electrodes (ie, positive and negative electrodes) in the present invention are typically semi-solid electrodes. Accordingly, the positive electrode and the negative electrode correspond to a semi-solid positive electrode and a semi-solid negative electrode, respectively.
  • the secondary battery of the present invention includes a semi-solid positive electrode and a semi-solid negative electrode, and at least one of the semi-solid positive electrode and the semi-solid negative electrode corresponds to the semi-solid electrode.
  • semi-solid electrode is meant that the electrode layer (particularly the material) is a mixture of solid and liquid phases, such as slurries, colloidal suspensions, emulsions, gels, or It may have the form of micelles or particle suspensions.
  • the electrode layer (that is, the semi-solid electrode layer) of the semi-solid electrode is specifically composed of a slurry containing an electrode active material (usually solid phase particles) and an electrolytic solution (usually a liquid phase), and further includes a conductive material. Additives such as auxiliaries (usually solid phase particles) may also be included.
  • a semi-solid electrode layer does not contain a binder for binding and/or fixing the electrode active materials together, unlike conventional binder-bonded electrode layers.
  • the electrode (especially the electrode layer) does not contain such a binder, it is possible to avoid an increase in electrical resistance due to the binder, and to achieve a higher capacity secondary battery. can.
  • the semi-solid electrode (particularly the semi-solid electrode layer) is not strictly prohibited from containing a binder.
  • the present invention does not preclude inclusion of a trace amount of binder as an impurity unintentionally mixed into the electrode layer during the manufacturing process, and a support base material for supporting the carbon material contained in the carbon layer.
  • the content of the binder contained in the semi-solid electrode (especially the semi-solid electrode layer) is 0.1% by mass or less, particularly 0.01% by mass or less, relative to the total amount of the semi-solid electrode layer. There may be.
  • the content of the binder may be within the above range for each of the semi-solid positive electrode layer and the semi-solid negative electrode layer (especially the semi-solid positive electrode layer).
  • An embodiment of the present invention includes a semi-solid electrode having a semi-solid electrode layer comprising an electrode active material, a conductive aid, and an electrolyte, and a current collector, the semi-solid electrode comprising a semi-solid electrode layer and a current collector It has a carbon layer between
  • a carbon layer is a layer containing a carbon material and a supporting base material (hereinafter referred to as a supporting base material) for supporting the carbon material.
  • the supporting base material is a material for dispersing and fixing the carbon material in the base material, and may be a material included in a so-called binder.
  • a support matrix for example, a macromolecule such as a polymer (for example, so-called plastic or rubber) is used. Due to these characteristics, the carbon layer may be a polymer layer in which carbon material is dispersed. Note that the carbon layer may also be referred to as a carbon coat layer.
  • the carbon layer 6 is provided between the semi-solid electrode layer 7 and the collector 5 .
  • the carbon layer 6 is formed in direct contact with the surface of the current collector 5 and also in direct contact with the semi-solid electrode layer 7 . Therefore, the frequency of contact between the carbon material in the carbon layer 6 and the current collector 5 becomes relatively high (the region indicated by 8 in FIG. 1), and the frequency of contact between the semi-solid electrode layer 7 and the carbon material in the carbon layer 6 increases. is also relatively high. As a result, the interfacial resistance between the semi-solid electrode layer and current collector 5 is relatively low, and the rate characteristics are sufficiently excellent.
  • the conventional secondary battery 10' as shown in FIG.
  • the frequency of contact between the current collector 5' and the carbon material in the semi-solid electrode layer 7' is relatively low (indicated by 8' in FIG. 2). region).
  • the interfacial resistance between the semi-solid electrode layer and the current collector becomes relatively high, resulting in poor rate characteristics.
  • the carbon layer 6 of FIG. 1 also includes a support base material.
  • a carbon material is a substance whose main component is carbon (C).
  • the carbon material is not particularly limited as long as it has conductivity, but carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon nanotubes and gas phase At least one selected from carbon fibers such as growing carbon fibers can be mentioned.
  • Carbon black is preferably used as the carbon material from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
  • the shape of the carbon material is not particularly limited, and any shape such as spherical, plate-like, and fibrous may be used.
  • the content of the carbon material contained in the carbon layer is preferably 20% by volume or more with respect to the total amount of the carbon layer. % by volume or less, more preferably 30% to 55% by volume, more preferably 35% to 50% by volume, particularly preferably 35% to 45% by volume.
  • the total amount of the carbon layer means the total content of each component (for example, the carbon material and the supporting base material) that constitutes the carbon layer.
  • the value measured by the following method is used for the content of the carbon material contained in the carbon layer. It is obtained by calculating the ratio of the area of the carbon material contained in the carbon layer to the total area of the carbon layer from a cross-sectional image of the carbon layer observed by SEM.
  • the average particle diameter of the carbon material contained in the carbon layer is not particularly limited.
  • the particle size of the carbon material is preferable from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
  • the support matrix may contain one or more polymers.
  • the supporting matrix is, for example, polyacrylonitrile, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, Polymers such as polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, CMC, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene and/or polycarbonate, or mixtures thereof may be mentioned.
  • the support base material preferably contains CMC and styrene-butadiene rubber from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
  • the content of the supporting base material contained in the carbon layer is preferably 30% by volume or more with respect to the total amount of the carbon layer, from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics. It is 90 volume % or less, more preferably 40 volume % or more and 80 volume % or less, still more preferably 50 volume % or more and 70 volume % or less, and particularly preferably 55 volume % or more and 65 volume % or less.
  • the content of the supporting matrix relative to the total amount of the carbon layer is the content (% by volume) of the two or more types of polymers relative to the total amount of the carbon layer. It can be a total value.
  • the supporting base material contains two or more types of polymers
  • the content ratio of each of the two or more types of polymers contained in the supporting base material is not particularly limited. From the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics, two or more types of polymers contained in the supporting base material are contained in equal amounts. is preferred.
  • the carbon layer may be insoluble in the electrolyte contained in the semi-solid electrode.
  • the supporting base material contained in the carbon layer does not have to be soluble in the solvent of the electrolytic solution contained in the semi-solid electrode layer.
  • “Not soluble” means that 0.001 g or less of the supporting base material dissolves per 1 mL of the solvent of the electrolytic solution contained in the semi-solid electrode layer at 20° C. ⁇ 5, for example.
  • the supporting base material that dissolves per 1 mL of the solvent of the electrolyte contained in the semi-solid electrode layer at 20 ° C. ⁇ 5 is , preferably 0.0001 g or less, particularly preferably 0.00001 g or less.
  • the thickness of the carbon layer is preferably 0.1 ⁇ m or more and 10 ⁇ m or less, more preferably 0.3 ⁇ m or more and 8 ⁇ m or less, from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics. It is preferably 0.5 ⁇ m or more and 5 ⁇ m or less, particularly preferably 0.75 ⁇ m or more and 2 ⁇ m or less.
  • the thickness of the carbon layer may be measured, for example, by length measurement from a cross-sectional SEM image.
  • the carbon layer is provided in the semi-solid electrode. Specifically, the carbon layer is provided between the semi-solid electrode layer and the current collector. In other words, the carbon layer is formed on the current collector. From the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics, the carbon layer is preferably formed so as to be in close contact with the current collector.
  • At least one of the semi-solid positive electrode and the semi-solid negative electrode corresponds to the above-described semi-solid electrode having a carbon layer.
  • the carbon layer does not necessarily have to be provided on both the semi-solid positive electrode and the semi-solid negative electrode. good.
  • a carbon layer may be provided on each of the positive electrode and the negative electrode.
  • the carbon layer may be provided on the positive electrode and the carbon layer may not be provided on the negative electrode.
  • the carbon layer may not be provided on the positive electrode and the carbon layer may be provided on the negative electrode.
  • a carbon layer is usually provided at least on the positive electrode.
  • the “semi-solid electrode layer”, “current collector”, and “electrolyte” are respectively “semi-solid positive electrode layer”, “positive electrode current collector”, and “ It corresponds to “positive electrode electrolyte”.
  • the “semisolid electrode layer”, the “current collector”, and the “electrolyte” are respectively the “semisolid negative electrode layer”, the “negative electrode current collector”, and the It corresponds to a "negative electrode electrolyte”.
  • the method of providing the carbon layer on the current collector is not particularly limited.
  • a slurry in which a carbon material and a supporting base material are dispersed (the supporting base material may be dissolved in the slurry) is applied on a current collector and dried to form a carbon layer on the current collector.
  • the method of applying the slurry onto the current collector is not particularly limited, but for example, a doctor blade method may be used.
  • a carbon layer is usually formed by being fixed (or fixed) to a current collector.
  • the secondary battery of the present invention Since the secondary battery of the present invention has the carbon layer between the electrode layer and the current collector, the interfacial resistance between the electrode layer and the current collector can be reduced. Therefore, even if the electrode layer has a low electrical conductivity and the interfacial resistance between the electrode layer and the current collector is more rate-determining, the secondary battery of the present invention has a low interfacial resistance between the electrode layer and the current collector. It is possible to improve the characteristics. That is, even if the secondary battery of the present invention has the conductivity of the electrode layer such that a conventional secondary battery cannot exhibit sufficient rate characteristics, the secondary battery of the present invention has the electrode layer and the current collector. The rate performance is much better due to the lower interfacial resistance of .
  • the secondary battery of the present invention exhibits much better rate characteristics than conventional secondary batteries when the conductivity of the electrode layer is lower.
  • the conductivity of the semisolid positive electrode layer may be less than 5.0 ⁇ 10 ⁇ 2 S/cm, preferably less than 3.5 ⁇ 10 ⁇ 2 S/cm, more It is preferably less than 1.0 ⁇ 10 ⁇ 2 S/cm, more preferably less than 0.5 ⁇ 10 ⁇ 2 S/cm, particularly preferably less than 0.25 ⁇ 10 ⁇ 2 S/cm, particularly preferably less than 0.25 ⁇ 10 ⁇ 2 S/cm. It may be less than 15 ⁇ 10 ⁇ 2 S/cm.
  • the conductivity of the semisolid negative electrode layer may be less than 5.0 ⁇ 10 ⁇ 2 S/cm, preferably less than 3.5 ⁇ 10 ⁇ 2 S/cm, more It is preferably less than 1.0 ⁇ 10 ⁇ 2 S/cm, more preferably less than 0.5 ⁇ 10 ⁇ 2 S/cm, particularly preferably less than 0.25 ⁇ 10 ⁇ 2 S/cm, particularly preferably less than 0.25 ⁇ 10 ⁇ 2 S/cm. It may be less than 15 ⁇ 10 ⁇ 2 S/cm.
  • the conductivity of the electrode layer becomes lower, the interface resistance between the electrode layer and the current collector becomes more rate-determining, and the drop in rate characteristics becomes more pronounced.
  • a value measured by, for example, the following method is used.
  • a dielectric measurement jig is attached to a rheometer (Discovery HR-1) manufactured by TA Instruments, and an impedance analyzer EC-Lab-BI-001 is connected to measure the volume resistivity of the electrode layer. conductivity.
  • the measurement is performed by multiplying the slope ( ⁇ /cm) between the resistance value and the gap obtained at 100 kHz by changing the gap to 500, 300, and 100 ⁇ m with a rheometer by the area (cm 2 ) of the measurement jig plate. I asked for it.
  • the conductivity of the electrode layer can be controlled by adjusting the amount of conductive aid contained in the electrode layer.
  • the electrical conductivity of the electrode layer can be made lower by reducing the amount of the conductive aid contained in the electrode layer.
  • the electrical conductivity of the electrode layer can be increased by increasing the amount of the conductive aid contained in the electrode layer.
  • the positive electrode active material contained in the positive electrode and the negative electrode active material contained in the negative electrode are substances that are directly involved in the transfer of electrons in the secondary battery, and are the main materials of the positive and negative electrodes that are responsible for charging and discharging, that is, the battery reaction. More specifically, ions are brought to the electrolytic solution due to the “positive electrode active material contained in the positive electrode” and the “negative electrode active material contained in the negative electrode”, and the ions move between the positive electrode and the negative electrode. Electrons are transferred to the battery and charged/discharged.
  • mediator ions are not particularly limited as long as they can be charged and discharged, and examples thereof include lithium ions or sodium ions (especially lithium ions).
  • the positive and negative electrodes may in particular be electrodes capable of intercalating and deintercalating lithium ions. That is, the secondary battery of the present invention may be a secondary battery in which charging and discharging are performed by moving lithium ions between the positive electrode active material and the negative electrode active material via the electrolyte. When lithium ions are involved in charging and discharging, the secondary battery according to the present invention corresponds to a so-called "lithium ion battery".
  • the positive electrode active material of the positive electrode is preferably made of, for example, granular material. Furthermore, it is also preferable that the positive electrode (especially the positive electrode layer) contains a conductive aid in order to facilitate the transfer of electrons that promote the battery reaction.
  • the negative electrode active material of the negative electrode is preferably made of, for example, a granular material, and a conductive aid may be contained in the negative electrode (especially the negative electrode layer) in order to facilitate the transfer of electrons that promote the battery reaction. . Because of such a configuration in which a plurality of components are contained, the positive electrode layer and the negative electrode layer can also be referred to as a "positive electrode mixture layer" and a "negative electrode mixture layer", respectively.
  • the semi-solid electrode layer contains an electrode active material, a conductive aid, and an electrolytic solution. Since the semi-solid electrode does not undergo a pressing process, it becomes necessary to add a larger amount of conductive aid than necessary to the electrode layer in order to sufficiently reduce the interfacial resistance between the semi-solid electrode layer and the current collector. obtain. If the amount of the conductive aid is increased, the amount of electrolytic solution required to impart fluidity to the semi-solid electrode layer is increased because the conductive aid has a high liquid trapping property. If the amount of the conductive agent in the electrode layer is increased and the amount of the electrolytic solution is also increased, the amount of active material in the electrode layer is relatively decreased, resulting in a further decrease in energy density.
  • the energy density here means the active material ratio in the electrode layer.
  • the amount of the conductive additive contained in the electrode layer is reduced, the amount of electrolytic solution required to impart fluidity to the semi-solid electrode layer is reduced.
  • the amount of the conductive agent in the electrode layer is reduced and the amount of the electrolytic solution is also reduced, the amount of active material is relatively increased and the energy density is further increased. Since the secondary battery of the present invention has a carbon layer between the electrode layer and the collector, the interfacial resistance between the semi-solid electrode layer and the collector is low even when the amount of the conductive aid is relatively small. , better rate characteristics.
  • the secondary battery of the present invention can reduce the amount of conductive aid in the electrode layer while maintaining better rate characteristics, and also reduces the amount of electrolytic solution required to impart fluidity. be able to. Also, in the secondary battery of the present invention, since the amounts of the conductive aid and the electrolyte can be relatively reduced, the amount of the active material in the electrode layer can be relatively increased, and the energy density can be further increased.
  • the positive electrode active material may be a material that contributes to absorption and release of lithium ions. From this point of view, the positive electrode active material may be, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material may be a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese and iron. That is, the positive electrode layer of the secondary battery according to the present invention may preferably contain such a lithium-transition metal composite oxide as a positive electrode active material.
  • the positive electrode active material may be lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or a transition metal thereof partially replaced by another metal. Although such a positive electrode active material may be contained as a single species, it may be contained in combination of two or more species. In a more preferred embodiment, the positive electrode active material contained in the positive electrode (especially the positive electrode layer) is lithium cobaltate.
  • the average particle size of the positive electrode active material is not particularly limited, and may be, for example, 1 ⁇ m or more and 100 ⁇ m or less, particularly 1 ⁇ m or more and 50 ⁇ m or less, further improving the energy density and further reducing the interfacial resistance between the electrode layer and the current collector.
  • the thickness is preferably 1 ⁇ m or more and 30 ⁇ m or less, more preferably 10 ⁇ m or more and 20 ⁇ m or less.
  • the average particle size of the positive electrode active material is the particle size D50 when the cumulative particle volume from the small particle size side reaches 50% of the total particle volume in the particle size distribution determined by the laser diffraction/scattering method.
  • the content of the positive electrode active material is usually 50% by mass or more and 90% by mass or less with respect to the total amount of the positive electrode layer, and further improves the energy density, further reduces the interfacial resistance between the electrode layer and the current collector, and improves the rate characteristics. From the viewpoint of further improvement, it is preferably 55% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 90% by mass or less, still more preferably 70% by mass or more and 90% by mass or less, and particularly preferably is 80% by mass or more and 90% by mass or less.
  • the total amount of the positive electrode layer means the total content of each component constituting the positive electrode layer (eg, positive electrode active material, conductive aid, electrolytic solution) excluding the current collector.
  • the content of the positive electrode active material in the positive electrode layer is determined, for example, by weighing a predetermined amount of the positive electrode layer and quantifying the amount of metal ions contained in the positive electrode active material by inductively coupled plasma mass spectrometry (ICP-MS). You may measure by converting into content of an active material.
  • ICP-MS inductively coupled plasma mass spectrometry
  • the conductive aid that can be contained in the positive electrode is not particularly limited, but includes carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon At least one selected from carbon fibers such as nanotubes and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives.
  • the conductive additive in the positive electrode layer is carbon black.
  • the positive electrode active material and conductive aid of the positive electrode layer are a combination of lithium cobaltate and carbon black.
  • the average particle size of the conductive aid contained in the positive electrode is not particularly limited, and may be, for example, 0.1 ⁇ m or more and 20 ⁇ m or less, particularly 0.1 ⁇ m or more and 10 ⁇ m or less. From the viewpoint of further reducing the interfacial resistance with and further improving the rate characteristics, the thickness is preferably 0.5 ⁇ m or more and 8 ⁇ m or less, more preferably 1 ⁇ m or more and 5 ⁇ m or less.
  • the average particle size of the conductive additive contained in the positive electrode is the particle size distribution determined by the laser diffraction/scattering method when the cumulative particle volume from the small particle size side reaches 50% of the total particle volume.
  • the particle size is D50.
  • the content of the conductive aid contained in the positive electrode is usually 0.1% by mass or more and 10% by mass or less with respect to the total amount of the positive electrode layer, further improving the energy density, the electrode layer and the current collector From the viewpoint of further reducing the interfacial resistance with the It is preferably 0.5% by mass or more and 2% by mass or less.
  • the content of the conductive aid in the positive electrode layer may be measured, for example, by thermogravimetric differential thermal analysis TG-DTA.
  • the negative electrode active material may be a material that contributes to intercalation and deintercalation of lithium ions.
  • the negative electrode active material may be, for example, various carbon materials, oxides, or lithium alloys.
  • various carbon materials for the negative electrode active material include graphite (natural graphite, artificial graphite), hard carbon, soft carbon, diamond-like carbon, and the like. In particular, graphite is preferred because of its high electronic conductivity.
  • the oxide of the negative electrode active material at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide and lithium oxide can be used.
  • the lithium alloy of the negative electrode active material may be any metal that can be alloyed with lithium, such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn It may be a binary, ternary or higher alloy of a metal such as La and lithium. Such an oxide is preferably amorphous as its structural form. This is because deterioration due to non-uniformity such as grain boundaries or defects is less likely to occur.
  • the negative electrode active material of the negative electrode is artificial graphite.
  • the average particle size of the negative electrode active material is not particularly limited, and may be, for example, 0.5 ⁇ m or more and 50 ⁇ m or less, particularly 1 ⁇ m or more and 40 ⁇ m or less. From the viewpoint of further reduction and further improvement of rate characteristics, the thickness is preferably 2 ⁇ m or more and 30 ⁇ m or less, more preferably 5 ⁇ m or more and 20 ⁇ m or less.
  • the average particle size of the negative electrode active material is the particle size D50 when the cumulative particle volume from the small particle size side reaches 50% of the total particle volume in the particle size distribution obtained by the laser diffraction/scattering method.
  • the content of the negative electrode active material is usually 10% by mass or more and 90% by mass or less with respect to the total amount of the negative electrode layer, further improving the energy density and further reducing the interfacial resistance between the electrode layer and the current collector, and From the viewpoint of further improving rate characteristics, it is preferably 30% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 90% by mass or less, It is more preferably 70% by mass or more and 90% by mass or less, and particularly preferably 80% by mass or more and 90% by mass or less.
  • the total amount of the negative electrode layer means the total content of each component constituting the negative electrode layer (for example, the negative electrode active material, the conductive aid, and the electrolytic solution, excluding the current collector).
  • the conductive aid that can be contained in the negative electrode is not particularly limited, but thermal black, furnace black, channel black, carbon black such as ketjen black and acetylene black, carbon nanotubes and At least one selected from carbon fibers such as vapor-grown carbon fibers, powders of metals such as copper, nickel, aluminum and silver, and polyphenylene derivatives.
  • the average particle size of the conductive aid contained in the negative electrode is not particularly limited, and may be, for example, 0.1 ⁇ m or more and 20 ⁇ m or less, particularly 0.1 ⁇ m or more and 10 ⁇ m or less. From the viewpoint of further reducing the interfacial resistance with and further improving the rate characteristics, the thickness is preferably 0.5 ⁇ m or more and 8 ⁇ m or less, more preferably 1 ⁇ m or more and 5 ⁇ m or less.
  • the average particle size of the conductive aid contained in the negative electrode is the particle size distribution determined by the laser diffraction/scattering method when the cumulative particle volume from the small particle size side reaches 50% of the total particle volume.
  • the particle size is D50.
  • the content of the conductive aid contained in the negative electrode (especially the negative electrode layer) is usually 0.1% by mass or more and 10% by mass or less with respect to the total amount of the negative electrode layer, and further improvement in energy density is achieved by combining the electrode layer and the current collector. From the viewpoint of further reducing the interfacial resistance with and further improving the rate characteristics, it is preferably 0.1% by mass or more and 2% by mass or less, more preferably 0% by mass or more and 2% by mass or less, and still more preferably It is 0% by mass. That the content of the conductive aid contained in the negative electrode (especially the negative electrode layer) is 0% by mass means that the negative electrode (especially the negative electrode layer) does not contain the conductive aid.
  • the electrolytic solution contained in the positive electrode and the electrolytic solution contained in the negative electrode usually have the same composition.
  • the electrolyte assists the movement of metal ions released from the electrode active material (positive electrode active material/negative electrode active material).
  • the electrolyte may be a "non-aqueous" electrolyte such as an organic electrolyte and an organic solvent, or an "aqueous” electrolyte containing water.
  • the secondary battery of the present invention is preferably a non-aqueous electrolyte secondary battery in which an electrolytic solution containing a "non-aqueous" solvent and a solute is used as the electrolytic solution.
  • the electrolytic solution may have a form such as liquid or gel (in this specification, the "liquid" non-aqueous electrolytic solution is also referred to as "non-aqueous electrolytic solution").
  • a specific solvent for the non-aqueous electrolyte is not particularly limited, and may contain at least carbonate.
  • Such carbonates may be cyclic carbonates and/or linear carbonates.
  • cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC). be able to.
  • chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC) and dipropyl carbonate (DPC).
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethylmethyl carbonate
  • DPC dipropyl carbonate
  • a combination of cyclic carbonates and chain carbonates is used as the non-aqueous electrolyte, for example, a mixture of ethylene carbonate and ethylmethyl carbonate is used.
  • Li salts such as LiPF 6 and LiBF 4 are preferably used as a specific solute of the non-aqueous electrolyte. In a preferred embodiment, it is LiPF6 .
  • the concentration of the solute in the electrolytic solution is not particularly limited, and may be, for example, 0.1M or more and 10M or less, particularly 0.5M or more and 3M or less. M means mol/L.
  • the electrolyte content in the semi-solid electrode layer affects the fluidity of the semi-solid electrode layer. For example, increasing the electrolyte content in the semi-solid electrode further increases the fluidity of the semi-solid electrode layer. On the other hand, when the electrolyte content in the semi-solid electrode is reduced, the fluidity of the semi-solid electrode layer is further reduced. When the content of the electrolyte contained in the semi-solid electrode layer is increased with respect to the total amount of the semi-solid electrode layer, the content of the active material contained in the semi-solid electrode layer becomes relatively small, resulting in a smaller energy density.
  • the content of the electrolyte contained in the semi-solid electrode layer is reduced relative to the total amount of the semi-solid electrode layer, the content of the active material contained in the semi-solid electrode layer is relatively increased, resulting in a higher energy density. growing.
  • the content of the electrolyte in the positive electrode (especially the positive electrode layer) and the negative electrode (especially the negative electrode layer) is adjusted from the viewpoint of further improving the energy density, further reducing the interfacial resistance between the electrode layer and the current collector, and further improving the rate characteristics.
  • the content of the electrolytic solution contained in the positive electrode is usually preferably 30% by volume or more and 70% by volume or less, more preferably 33% by volume or more and 67% by volume, based on the total amount of the positive electrode layer.
  • the content of the electrolytic solution contained in the negative electrode is usually preferably 30% by volume or more and 70% by volume or less, more preferably 33% by volume or more and 67% by volume, based on the total amount of the negative electrode layer.
  • the thickness of the electrode layer is not particularly limited, and may be appropriately selected according to the desired battery capacity.
  • the thickness of the electrode layer (especially the thickness of the electrode layer per one main surface (single side) of the current collector described later) is such that, for example, the capacity per electrode area of one side in the secondary battery of the present invention is within the range described later.
  • the thickness is usually 80 ⁇ m or more, and may be 150 ⁇ m or more and 500 ⁇ m or less.
  • the thickness of the electrode layer includes the thickness of the positive electrode layer and the thickness of the negative electrode layer, each of which may be independently selected. As the thickness of the electrode layer, an average value of thicknesses at 50 arbitrary locations in the completed secondary battery is used.
  • An electrode (especially a semi-solid electrode) is usually provided with an electrode layer (especially a semi-solid electrode layer) on at least one side (preferably both sides) of a current collector.
  • the constituent material of the current collector is not particularly limited as long as it has conductivity. For example, an alloy containing one metal or two or more metals selected from the group consisting of copper, aluminum, stainless steel, etc. good.
  • the current collector of the positive electrode (that is, the positive electrode current collector) is preferably made of aluminum from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
  • the current collector of the negative electrode (that is, the negative electrode current collector) is preferably made of copper from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
  • the thickness of the current collectors of the positive electrode and the negative electrode is not particularly limited, and may be, for example, 1 ⁇ m or more and 300 ⁇ m or less, particularly 1 ⁇ m or more and 100 ⁇ m or less.
  • the secondary battery of the present invention is usually enclosed in an outer package.
  • the exterior body may be a flexible pouch (soft bag body) or a hard case (hard housing).
  • the outer package is preferably a flexible pouch from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
  • the flexible pouch is usually formed from a laminated film, and the periphery is heat-sealed to form a sealed portion.
  • the laminate film a film obtained by laminating a metal foil and a polymer film is generally used. Specifically, a three-layer structure composed of an outer layer polymer film/metal foil/inner layer polymer film is exemplified.
  • the outer layer polymer film is intended to prevent permeation of moisture or the like and damage to the metal foil due to contact and the like, and polymers such as polyamide and polyester can be suitably used.
  • the metal foil is for preventing the permeation of moisture and gas, and foils of copper, aluminum, stainless steel, etc. can be suitably used.
  • the inner layer polymer film protects the metal foil from the electrolyte to be housed inside and melts and seals the opening at the time of heat sealing, and polyolefin or acid-modified polyolefin can be suitably used.
  • the thickness of the laminate film is not particularly limited, and is preferably 1 ⁇ m or more and 1 mm or less, for example.
  • the exterior body is usually heat-sealed at its periphery in plan view. More specifically, when the exterior body is made of two rectangular exterior body materials, the exterior body is usually heat-sealed at its four sides in a plan view.
  • the exterior body is made of a sheet of exterior body material having a rectangular shape, one of the four sides of the exterior body in a plan view is usually formed by folding the exterior body material.
  • the hard case is usually made of a metal plate, and the peripheral edge is irradiated with a laser to form a seal.
  • the metal plate metal materials such as aluminum, nickel, iron, copper, and stainless steel are generally used.
  • the thickness of the metal plate is not particularly limited, and is preferably 1 ⁇ m or more and 1 mm or less, for example. Sealing of the metal plates may be achieved by lasing their overlap at the perimeter.
  • the secondary battery of the present invention is effective in increasing capacity. Since the electrode layer is a semi-solid electrode layer and has fluidity, the thickness of the electrode layer can be stably and easily increased simply by increasing the injection amount. From such a viewpoint, the capacity per electrode area on one side of the secondary battery of the present invention is preferably 4 mAh/cm 2 or more, more preferably 5 mAh/cm 2 or more and 20 mAh/cm 2 or less. Since the electrode layer is a semi-solid electrode layer in the present invention, the capacity per electrode area may be the capacity per current collector area. The capacity per electrode area of the positive electrode and the negative electrode may be independently within the above range. When the current collector has electrode layers on both sides, the capacity per electrode area is the capacity per one side. The capacity per electrode area of the secondary battery can be obtained, for example, by dividing the capacity of the secondary battery obtained by 0.2 CA discharge by the electrode area.
  • the capacity per electrode area in the secondary battery of the present invention may be the active material capacity per electrode area.
  • the capacity per electrode area may be controlled, for example, by adjusting the amount of slurry containing the active material injected into the electrode. Specifically, the capacity per electrode area may be controlled by adjusting the amount of slurry containing the active material injected into the electrode so as to achieve a predetermined active material capacity per electrode area.
  • the capacities per electrode area include both positive and negative electrodes, and the capacities per area of the positive and negative electrodes can be controlled in the same manner as the control method described above.
  • the secondary battery of the present invention may further have a protective layer (not shown) on the outer surface of the outer package.
  • the secondary battery 10 of the present invention can be manufactured by a method including the following steps: A preparation step of mixing an electrode active material, a conductive aid, and an electrolytic solution to prepare an electrode layer slurry (that is, a positive electrode layer slurry and a negative electrode layer slurry); Carbon layer forming step of forming a carbon layer on the current collector; A coating step of coating an electrode layer slurry on a current collector having a carbon layer to form electrodes (i.e., positive and negative electrodes); a stacking step of stacking to form a stack such that the separator is disposed between the electrodes (that is, between the positive electrode and the negative electrode); and an encapsulating step of encapsulating the stack in an outer package.
  • the manufacturing method of the secondary battery of the present invention may usually include the following steps immediately after the coating step: A welding process that welds a tab to an electrode.
  • the manufacturing method of the secondary battery of the present invention may further include the following steps in sequence after the encapsulation step: a charging/discharging step of forming a solid electrolyte interfacial coating on the surface of the negative electrode active material by an initial charging treatment to form a secondary battery precursor; and an aging step of aging the secondary battery precursor.
  • the positive electrode active material, conductive aid, electrolytic solution, and desired additives are mixed and dispersed to prepare the positive electrode layer slurry.
  • the negative electrode active material, the electrolytic solution, and optionally the conductive aid are mixed and dispersed to prepare the negative electrode layer slurry.
  • a support base material in which a carbon material is dispersed is applied onto the positive electrode current collector and dried to form a carbon layer on the positive electrode current collector.
  • the slurry for the positive electrode layer is applied to the positive electrode current collector having the carbon layer to form the positive electrode. Further, the negative electrode layer slurry is applied to the negative electrode current collector to form the negative electrode. In the formation of the positive electrode and the negative electrode, the electrode layer slurry is applied independently to at least one surface (preferably both surfaces) of the current collector.
  • a welding process may be performed.
  • the positive electrode tab is welded to the positive electrode.
  • a negative electrode tab is welded to the negative electrode.
  • the material constituting the positive electrode tab and the negative electrode tab is not particularly limited as long as it has conductivity, and may be selected from, for example, the same material as the material constituting the current collector.
  • the positive electrode tab is preferably made of aluminum.
  • the negative electrode tab is preferably made of copper.
  • the welding step may be performed before (particularly immediately before) the coating step.
  • the positive electrode and the negative electrode are stacked such that the positive electrode and the negative electrode are alternately arranged and the separator is arranged between them to produce a laminate.
  • the laminate is sandwiched between outer packaging materials.
  • the sandwiching is not particularly limited as long as the exterior bodies are arranged at the top and bottom of the laminate in plan view, and may be achieved, for example, by the following method (i) or (ii): Method (i) Sandwiching the laminate with two sheets of armor material; Method (ii) The laminate is housed in a bag-shaped exterior body having an opening on one side in a plan view, which is formed by sealing in advance. In the method (i), instead of using two sheets of armor material, one continuous sheet of armor material may be folded back.
  • the overlapped portion at the peripheral edge of the exterior material is sealed, and the interior of the exterior is evacuated.
  • the inside of the exterior body is evacuated while sealing the peripheral edges of the exterior body material at their overlapped portions.
  • the opening of the bag-shaped outer package is sealed by the overlapped portion thereof, and the inside of the outer package is evacuated.
  • the overlapping portion is the overlapping portion of the exterior body materials.
  • a charge/discharge step and an aging step may be performed.
  • a solid electrolyte interface coating (hereinafter referred to as “SEI coating”) is formed on the surface of the negative electrode active material by an initial charging process.
  • the initial charging treatment is the initial charging treatment for the purpose of forming an SEI film on the surface of the negative electrode active material, and is also called conditioning treatment or formation treatment.
  • the SEI coating is formed by reductive decomposition of the additive contained in the electrolytic solution on the surface of the negative electrode active material in this treatment, and prevents further decomposition of the additive on the surface of the negative electrode active material during use as a secondary battery. do.
  • SEI coatings typically contain one or more materials selected from the group consisting of LiF, Li2CO3 , LiOH and LiOCOOR, where R represents a monovalent organic group, such as an alkyl group.
  • charging should be performed at least once. Normally, charging and discharging are performed one or more times. One charge/discharge includes one charge and one subsequent discharge. When charging/discharging is performed two or more times, charging/discharging is repeated that number of times. The number of times of charge/discharge performed in this process is usually 1 or more and 3 or less.
  • the charging method may be a constant current charging method, a constant voltage charging method, or a combination thereof.
  • constant voltage charging and constant voltage charging may be repeated during one charge.
  • Charging conditions are not particularly limited as long as the SEI film is formed. From the viewpoint of further improving the uniformity of the thickness of the SEI film, it is preferable to perform constant voltage charging after performing constant current charging.
  • the discharge method may generally be a constant current discharge method, a constant voltage discharge method, or a combination thereof.
  • Discharge conditions are not particularly limited as long as the SEI coating is formed. From the viewpoint of further improving the uniformity of the thickness of the SEI coating, constant current discharge is preferably performed.
  • the secondary battery is usually maintained at a temperature within the range of 25° C. or higher and 100° C. or lower, preferably 35° C. or higher and 90° C. or lower, more preferably 40° C. or higher and 85° C. or lower. be done.
  • the SEI coating stabilization process is a process for stabilizing the SEI coating by leaving the secondary battery in an open circuit state after the initial charging process.
  • the temperature of the secondary battery in the stabilization process is not particularly limited, and may be maintained, for example, within the range of 15°C or higher and 80°C or lower. From the viewpoint of further stabilizing the SEI coating, the secondary battery is preferably maintained at a temperature within the range of 20° C. or higher and 75° C. or lower, and more preferably maintained at a temperature of 25° C. or higher and 70° C. or lower. Specifically, the temperature can be maintained within the above range by leaving the secondary battery in a space set to a constant temperature.
  • the standing time is not particularly limited as long as the stabilization of the SEI coating is promoted, and is usually 10 minutes or more and 30 days or less, and from the viewpoint of further stabilization of the SEI coating, preferably 30 minutes or more and 14 days. It is within the following range, and more preferably within the range of 1 hour or more and 7 days or less.
  • the manufacturing method of the secondary battery according to the present invention includes only the preparation step, the carbon layer forming step, and the coating step as the electrode manufacturing steps, and the welding step, the laminating step, the encapsulating step, and the charging/discharging step as the assembling steps. It only includes a process and an aging process.
  • the manufacturing method of a secondary battery including a conventional binder-bonded electrode layer includes, as an electrode manufacturing process, a preparation step of preparing an electrode layer-forming coating solution; A coating step of coating on; a drying step of drying the coated electrode layer forming coating solution; a pressing step of consolidating the electrode layer; a slitting step of cutting the electrode to a desired width;
  • the electrode is cut into a desired shape and size to form an electrode, and the assembly process includes a welding process in which a tab is welded to the electrode;
  • Example 1 Semi-solid electrode type secondary battery
  • the carbon layer on the surface of the Al foil was prepared by dispersing carbon black with an average particle size of 0.6 ⁇ m, CMC, and SBR at 40:30:30 (vol%) in water using a die coater. It was obtained by coating and drying the surface of Al foil so as to have a thickness of 1 ⁇ m.
  • a solution obtained by dissolving artificial graphite with an average particle size of 10.2 ⁇ m as the negative electrode active material and LiPF 6 at 1 M in a mixed solvent (EC: EMC 25: 75 vol) as the electrolyte solution, at a weight ratio of 60.0. : 40.0 to obtain a fluid negative electrode layer slurry.
  • the negative electrode layer slurry was applied to one side of a 12 ⁇ m thick Cu foil by a doctor blade method to obtain a negative electrode of 10.2 cm ⁇ 10.2 cm so that the negative electrode active material capacity on one side was 5.4 mAh/cm 2 .
  • the tab-welded positive electrode and negative electrode were attached to each other with a separator interposed therebetween, sandwiched between aluminum laminates, and vacuum-sealed. After charging and discharging at 0.2 CA, the battery was charged to SOC 70% and subjected to aging treatment at 55° C. for 24 hours to complete a secondary battery with a capacity of about 500 mAh.
  • the content of the binder was 0.01% by mass or less with respect to the total amount of the semi-solid positive electrode layer in the secondary battery completed in this example.
  • the semi-solid negative electrode the binder content was 0.01% by mass or less with respect to the total amount of the semi-solid negative electrode layer in the secondary battery completed in this example.
  • Example 2 Semi-solid electrode type secondary battery
  • LiPF 6 an electrolyte mixed solvent
  • Lithium cobaltate (LCO) with an average particle size of 15 ⁇ m as a positive electrode active material, carbon black with an average particle size of 1 ⁇ m as a conductive agent, and PVdF as a binder were mixed in NMP at a weight ratio of 96:2:2. to obtain a positive electrode slurry.
  • LCO Lithium cobaltate
  • Negative electrode preparation Artificial graphite with an average particle size of 10 ⁇ m as a negative electrode active material, flake graphite with an average particle size of 3 ⁇ m as a conductive aid, and CMC and SBR as binders at a weight ratio of 96: 1: 3 (1.5 + 1.5) was dispersed in water to obtain a negative electrode slurry. Then, using a die coater, apply and dry one side of a 12 ⁇ m thick Cu foil so that the active material capacity on one side becomes 5.4 mAh / cm 2 , and then use a roll press machine so that the porosity becomes 23%. , and slit and cut to obtain a negative electrode of 10.2 cm x 10.2 cm.
  • the content of the binder was 2% by mass with respect to the total amount of the positive electrode layer in the secondary battery completed in this example.
  • Example 1 Semi-solid electrode type secondary battery
  • a secondary battery was obtained in the same manner as in Example 1, except that a normal Al foil having a thickness of 15 ⁇ m without a carbon layer was used as the Al foil to which the positive electrode layer slurry was applied in the production of the positive electrode.
  • Example 2 Semi-solid electrode type secondary battery
  • a secondary battery was obtained in the same manner as in Example 2, except that a normal Al foil having a thickness of 15 ⁇ m without a carbon layer was used as the Al foil to which the positive electrode layer slurry was applied in the production of the positive electrode.
  • the capacity retention rate X (0.2 CA discharge capacity ratio) was measured when various completed secondary batteries were discharged at 25° C. and 2 CA. ⁇ ; 85% ⁇ X (best); ⁇ ; 70% ⁇ X ⁇ 85% (good); ⁇ ; 50% ⁇ X ⁇ 70% (no practical problem); x; X ⁇ 50% (practically problematic).
  • Example 1 (Capacity retention rate X of Example 1)/(Capacity retention rate X of Comparative example 1)
  • Example 2 (Capacity retention rate X of Example 2)/(Capacity retention rate X of Comparative example 2)
  • Table 1 Symbols in Table 1 are as follows. *1: Blending, coating, drying, pressing, slitting, cutting *2: Tab welding, laminate fabrication, injection, vacuum impregnation, sealing, charge/discharge, aging *3: Blending, carbon layer formation, coating *4: Tab welding, laminate fabrication, encapsulation, charging/discharging, aging
  • the secondary batteries were manufactured in a very large area of 5.0 mAh/cm 2 .
  • Comparative Example 1 which was produced by a normal method including a binder, the resistance was high, and the rate characteristics and cycle characteristics were low.
  • Comparative Example 1 which uses a fluid electrode that does not contain a binder, the secondary battery manufacturing process can be significantly simplified and the 2CA capacity retention rate can be improved, but there is no carbon layer. Therefore, the interface resistance with the Al foil is high, and the rate characteristic is low.
  • Example 1 which uses an Al foil having a carbon layer, rate characteristics can be improved.
  • Comparative Example 2 the amount of conductive aid added to the positive electrode layer was further reduced, and although the active material ratio (energy density) in the electrode layer could be increased, the electrical conductivity of the electrode layer was a threshold value of 1. 0 ⁇ 10 ⁇ 2 S/cm, the decrease in the capacity retention ratio is remarkable compared to Comparative Example 1.
  • Example 2 the addition amount of the conductive aid is small, and the ratio of the active material in the mixture is high, and at the same time, the Al foil having the carbon layer is used, so a high level of rate characteristics is obtained.
  • the rate characteristic of Example 1 is about 1.8 times as large as the rate characteristic of Comparative Example 1.
  • FIG. The rate characteristic of Example 2 is about 5.1 times as large as the rate characteristic of Comparative Example 2.
  • FIG. When the conductivity of the electrode layer is lower than 1.0 ⁇ 10 ⁇ 2 S/cm, the resistance at the interface between the electrode layer and the current collector becomes more rate-determining. Therefore, the effect of the carbon layer increases in the conductivity range of 1.0 ⁇ 10 ⁇ 2 S/cm.
  • the secondary battery of the present invention can be used in various fields where battery use or power storage is assumed. Although merely an example, the secondary battery of the present invention can be used in the electronics packaging field.
  • the secondary battery according to one embodiment of the present invention is also used in the electric, information, and communication fields where mobile devices are used (for example, mobile phones, smartphones, smart watches, laptops, digital cameras, activity meters, arm computers, etc.). , electronic paper, wearable devices, RFID tags, card-type electronic money, small electronic devices such as smart watches, etc.), home and small industrial applications (e.g., electric tools, golf carts, home/nursing/industrial robots), large industrial applications (e.g. forklifts, elevators, harbor cranes), transportation systems (e.g.
  • hybrid vehicles electric vehicles, buses, trains, electrically assisted bicycles, Electric motorcycles, etc.
  • power system applications for example, various power generation, road conditioners, smart grids, general household installation type storage systems, etc.
  • medical applications medical equipment such as earphone hearing aids
  • medical applications dosing management systems, etc.
  • space/deep-sea applications for example, the fields of space probes, submersible research vessels, etc.

Abstract

The present invention provides a secondary battery in which the interfacial resistance between an electrode layer and a current collector is further reduced and substantially superior rate characteristics are obtained. The present invention relates to a secondary battery 10 including a semi-solid electrode 1 that has: a semi-solid electrode layer 7 including an electrode active material 2, a conductive auxiliary agent 3, and an electrolyte solution 4; and a current collector 5. The semi-solid electrode 1 has a carbon layer 6 between the semi-solid electrode layer 7 and the current collector 5.

Description

二次電池およびその製造方法Secondary battery and manufacturing method thereof
　本発明は二次電池、特に半固体電極を含む二次電池、およびその製造方法に関する。 The present invention relates to a secondary battery, particularly a secondary battery including a semi-solid electrode, and a manufacturing method thereof.
　従来、種々の電子機器の電源として、二次電池が用いられている。二次電池は一般的に外装体内に、正極層を有する正極および負極層を有する負極がセパレータを介して交互に積層された積層体ならびに電解液が収容された構造を有している。また正極および負極等の電極としては、電極活物質および導電助剤等を集電体上でバインダーにより結合させたバインダー結合型電極が使用されている。 Conventionally, secondary batteries have been used as power sources for various electronic devices. A secondary battery generally has a structure in which a laminate in which a positive electrode having a positive electrode layer and a negative electrode having a negative electrode layer are alternately laminated with separators interposed therebetween, and an electrolytic solution are accommodated in an exterior body. As electrodes such as the positive electrode and the negative electrode, binder-bonded electrodes are used in which an electrode active material, a conductive agent, and the like are bonded on a current collector with a binder.
　一方、製造コストの簡素化および削減、電極および二次電池における不活性構成要素の削減、ならびにエネルギー密度、電荷容量および全体性能の向上を目的として、バインダー結合型電極の代わりに、流動性を有するいわゆる半固体電極を用いた二次電池が知られている（例えば特許文献１）。 On the other hand, flowable alternatives to binder-bonded electrodes for the purpose of simplifying and reducing manufacturing costs, reducing inert components in electrodes and secondary cells, and improving energy density, charge capacity and overall performance A secondary battery using a so-called semi-solid electrode is known (for example, Patent Document 1).
特表２０１６－５００４６５号公報Japanese Patent Publication No. 2016-500465
　本発明の発明者等は、従来の二次電池においては、以下のような新たな問題が生じ得ることを見出した。 The inventors of the present invention have found that conventional secondary batteries may have the following new problems.
（１）バインダー結合型電極においては、バインダーが比較的多量に存在するため、バインダーの存在が、電子およびイオンの動きを妨げ、電気抵抗を高めた。このため、レート特性が低下した。 (1) In the binder-bonded electrode, since the binder was present in a relatively large amount, the presence of the binder hindered the movement of electrons and ions and increased the electrical resistance. As a result, rate characteristics deteriorated.
（２）バインダー結合型電極を含む二次電池の製造方法は、電極製造工程として、電極層形成用塗工液を調合する調合工程；電極層形成用塗工液を集電体に塗工する塗工工程；塗工された電極層を乾燥させる乾燥工程；電極前駆体を圧密化するプレス工程；電極前駆体を所望幅に裁断するスリット工程および電極前駆体を所望寸法に裁断し、電極を形成する裁断工程；を含み、組み立て工程として、電極にタブを接続する溶接工程；電極を、正極と負極とが交互に配置されつつそれらの間にセパレータが配置されるように積層して積層体を作製する積層工程；作製した積層体を外装体内に挟み込み、その外装体内に電解液を注入する注液工程；外装体内を真空に保持しつつ電解液を電極に含浸させる真空含浸工程；積層体を外装体に封入する封入工程；初期充電処理により負極活物質表面に固体電解質界面被膜を形成し、二次電池前駆体を形成する充放電工程；および二次電池前駆体をエージングするエージング工程を含む。このように複雑で長い製造プロセスは、設備投資および製造プロセスコストを増大させ、二次電池の製造コストを高めていた。 (2) A method for manufacturing a secondary battery including a binder-bonded electrode includes, as an electrode manufacturing step, a preparation step of preparing an electrode layer-forming coating solution; coating a current collector with an electrode layer-forming coating solution; A coating step; a drying step for drying the coated electrode layer; a pressing step for consolidating the electrode precursor; a slitting step for cutting the electrode precursor into a desired width; a cutting step to form; an assembling step, a welding step of connecting tabs to the electrodes; A lamination step of producing; a liquid injection step of sandwiching the produced laminate in an outer package and injecting an electrolytic solution into the outer package; a vacuum impregnation step of impregnating an electrode with an electrolytic solution while holding the outer package in a vacuum; An encapsulation step of enclosing in an outer package; a charging and discharging step of forming a solid electrolyte interfacial coating on the surface of the negative electrode active material by an initial charging treatment to form a secondary battery precursor; and an aging step of aging the secondary battery precursor. include. Such a complicated and lengthy manufacturing process increases equipment investment and manufacturing process costs, and increases the manufacturing costs of secondary batteries.
（３）半固体電極は、従来の電極よりも大幅に厚くすることが可能であるため、不活性材料（すなわち集電体およびセパレータ）に対する活物質の比率は、従来の電極を使用した２次電池と比べて、半固体電極を使用した電池では高くなり得る。これにより、半固体電極を含む２次電池の電荷容量およびエネルギー密度全体が、大幅に増加する。しかしながら、半固体電極を含む二次電池において、半固体状の電極はプレス工程を経ないため、電極層と集電体が十分に圧着されず、電極層と集電体の界面抵抗が大きくなり易い。このため、レート特性が低下した。電極層と集電体との界面抵抗を十分に下げるためには、電極層中に必要以上に多くの導電助剤を添加する必要が生じ得る。しかしながら、導電助剤は捕液性が高いため、電極に流動性を付与するには必要な電解液量が増加する。その結果として、エネルギー密度が低下した。 (3) Semi-solid electrodes can be made significantly thicker than conventional electrodes, so the ratio of active to inactive materials (i.e., current collectors and separators) is second to none using conventional electrodes. Compared to batteries, batteries using semi-solid electrodes can be expensive. This greatly increases the overall charge capacity and energy density of secondary batteries containing semi-solid electrodes. However, in a secondary battery including a semi-solid electrode, since the semi-solid electrode does not undergo a pressing process, the electrode layer and the current collector are not sufficiently crimped, and the interfacial resistance between the electrode layer and the current collector increases. easy. As a result, rate characteristics deteriorated. In order to sufficiently lower the interfacial resistance between the electrode layer and the current collector, it may be necessary to add an excessive amount of conductive aid to the electrode layer. However, since the conductive aid has a high liquid trapping property, the amount of electrolytic solution required to impart fluidity to the electrode increases. As a result, the energy density decreased.
　本発明は、レート特性がより優れるとともに、エネルギー密度により十分に優れた二次電池およびその製造方法を提供することを目的とする。エネルギー密度とは、例えば１つの電極層から生じ得るエネルギー量に関する特性であり、具体的には半固体電極層中の活物質の含有割合に応じて決定される特性あってもよい。レート特性とは、例えば高レートで放電した際の二次電池の容量維持率（例えば、高レートでの放電容量／基準レートでの放電容量に関する特性である）。 An object of the present invention is to provide a secondary battery with more excellent rate characteristics and sufficiently superior energy density, and a method for manufacturing the same. The energy density is, for example, a characteristic related to the amount of energy that can be generated from one electrode layer, and specifically, it may be a characteristic determined according to the content ratio of the active material in the semi-solid electrode layer. The rate characteristics are, for example, the capacity retention rate of a secondary battery when discharged at a high rate (for example, characteristics relating to discharge capacity at a high rate/discharge capacity at a standard rate).
　本発明はまた、レート特性がより優れるとともに、エネルギー密度により十分に優れ、かつより少ない製造工程で製造可能な二次電池およびその製造方法を提供することを目的とする。 Another object of the present invention is to provide a secondary battery that has superior rate characteristics, sufficiently superior energy density, and that can be manufactured with fewer manufacturing steps, and a method for manufacturing the same.
　本発明は、
　電極活物質、導電助剤および電解液を含む半固体電極層と、集電体とを有する半固体電極を含み、
前記半固体電極は、前記半固体電極層と前記集電体との間にカーボン層を有する、二次電池に関する。 The present invention
A semi-solid electrode having a semi-solid electrode layer containing an electrode active material, a conductive aid and an electrolytic solution, and a current collector,
The semi-solid electrode relates to a secondary battery having a carbon layer between the semi-solid electrode layer and the current collector.
　本発明はまた、
　上記二次電池を製造する方法であって、以下の工程を含む、二次電池の製造方法に関する：
　電極活物質、導電助剤および電解液を混合して、電極層用スラリーを調合する調合工程；
　集電体にカーボン層を形成するカーボン層形成工程；
　カーボン層を有する集電体に電極層用スラリーを塗布し、電極を形成する塗布工程；
　電極と電極の間にセパレータが配置されるように、積層し積層体を作製する積層工程；
　積層体を外装体に封入する封入工程。 The present invention also provides
A method for manufacturing the above secondary battery, which method includes the following steps:
A preparation step of mixing an electrode active material, a conductive aid and an electrolytic solution to prepare an electrode layer slurry;
Carbon layer forming step of forming a carbon layer on the current collector;
A coating step of coating an electrode layer slurry on a current collector having a carbon layer to form an electrode;
A lamination step of laminating and producing a laminate so that a separator is arranged between electrodes;
An enclosing step of enclosing the laminate in the outer package.
　本発明の二次電池においては、カーボン処理された集電体を用いることでプレス工程を経ない電極であっても、電極層と集電体の界面抵抗を下げられるため、レート特性により十分に優れている。また、本発明の二次電池はまた、導電助剤の添加量は電極層の導電性確保に必要な最小量で済むため、電極に流動性を持たせるための電解液量も少なくて済み、エネルギー密度を高めることもできる。
　本発明の二次電池においては、二次電池製造工程を著しく簡略化できるため設備投資コスト・製造プロセスコストを大幅に削減できる。本発明の二次電池はまた、電極に流動性を付与するために必要な電解液量が減少するため、エネルギー密度が増加する。本発明の二次電池はまた、バインダーを含まず低抵抗化が実現できるため、レート特性により十分に優れている。 In the secondary battery of the present invention, by using a carbon-treated current collector, the interfacial resistance between the electrode layer and the current collector can be reduced even if the electrode does not undergo a pressing process, so that the rate characteristics can be sufficiently improved. Are better. In addition, in the secondary battery of the present invention, the amount of the conductive agent added is the minimum amount necessary to ensure the conductivity of the electrode layer, so the amount of electrolytic solution for imparting fluidity to the electrode can be reduced. It is also possible to increase the energy density.
In the secondary battery of the present invention, the manufacturing process of the secondary battery can be significantly simplified, so that equipment investment costs and manufacturing process costs can be greatly reduced. The secondary battery of the present invention also has an increased energy density because the amount of electrolyte required to impart fluidity to the electrodes is reduced. Since the secondary battery of the present invention does not contain a binder and can achieve low resistance, it is sufficiently excellent in rate characteristics.
図１は、本発明の一実施態様に係る二次電池においてレート特性が向上するメカニズムを説明するための、当該二次電池の模式的断面図の一例である。FIG. 1 is an example of a schematic cross-sectional view of a secondary battery according to one embodiment of the present invention, for explaining the mechanism by which the rate characteristics are improved in the secondary battery. 図２は、従来の二次電池において、レート特性が低下するメカニズムを説明するための従来の二次電池の模式的断面図である。FIG. 2 is a schematic cross-sectional view of a conventional secondary battery for explaining the mechanism of deterioration of rate characteristics in the conventional secondary battery.
［二次電池］
　本発明は二次電池を提供する。本明細書中、「二次電池」という用語は充電および放電の繰り返しが可能な電池のことを指している。「二次電池」は、その名称に過度に拘泥されるものではなく、例えば、「蓄電デバイス」などの電気化学デバイスも包含し得る。本明細書でいう「平面視」とは、厚み方向（例えば電極およびセパレータの積層方向）に沿って対象物を上側または下側（特に上側）からみたときの状態（上面図または下面図）のことである。本明細書でいう「断面視」とは、厚み方向に対する垂直方向からみたときの断面状態（断面図）のことである。図面に示す各種の要素は、本発明の理解のために模式的に示したにすぎず、寸法比および外観などは実物と異なり得ることに留意されたい。本明細書で直接的または間接的に用いる“上下方向”、“左右方向”および“表裏方向”はそれぞれ、図中における上下方向、左右方向および表裏方向に対応した方向に相当する。特記しない限り、同じ符号または記号は、同じ部材または同じ意味内容を示すものとする。ある好適な態様では、鉛直方向下向き（すなわち、重力が働く方向）が「下方向」に相当し、その逆向きが「上方向」に相当すると捉えることができる。 [Secondary battery]
The present invention provides a secondary battery. As used herein, the term "secondary battery" refers to a battery that can be repeatedly charged and discharged. "Secondary battery" is not overly bound by its name, and can include, for example, electrochemical devices such as "power storage device." As used herein, the term “planar view” refers to a state (top view or bottom view) when an object is viewed from above or below (especially above) along the thickness direction (for example, the stacking direction of electrodes and separators). That is. The term "cross-sectional view" as used herein refers to a cross-sectional state (cross-sectional view) when viewed from a direction perpendicular to the thickness direction. It should be noted that the various elements shown in the drawings are only schematically shown for understanding the present invention, and that the dimensional ratios, appearances, etc. may differ from the actual ones. "Vertical direction", "horizontal direction" and "front and back direction" used directly or indirectly in this specification respectively correspond to the vertical direction, left and right direction and front and back direction in the drawings. Unless otherwise specified, identical symbols or symbols shall indicate identical items or identical meanings. In a preferred embodiment, the downward vertical direction (that is, the direction in which gravity acts) corresponds to the "downward direction", and the opposite direction corresponds to the "upward direction".
　本発明において二次電池を構成する各部材は、特記しない限り、正極側と負極側のそれぞれに配置される。例えば、電極は正極および負極を包含する。また例えば、電極活物質（または活物質）は正極活物質および負極活物質を包含する。また例えば、導電助剤は正極導電助剤および負極導電助剤を包含する。また例えば、電解液は正極電解液および負極電解液を包含する。なお、正極電解液および負極電解液は、同一組成の電解液を使用してもよい。 Unless otherwise specified, each member constituting the secondary battery in the present invention is arranged on each of the positive electrode side and the negative electrode side. For example, electrodes include positive and negative electrodes. Also, for example, an electrode active material (or active material) includes a positive electrode active material and a negative electrode active material. Further, for example, the conductive aid includes a positive electrode conductive aid and a negative electrode conductive aid. Also for example, the electrolyte includes a positive electrolyte and a negative electrolyte. Electrolyte solutions having the same composition may be used for the positive electrode electrolyte solution and the negative electrode electrolyte solution.
　以下、本発明の二次電池を、図面を用いて詳しく説明する。本発明の二次電池１０は、図１に示すように、半固体電極１を有して成る。図１の半固体電極は、半固体正極または半固体負極の一方を模式的に示している。当該半固体電極１は、半固体電極層７、集電体５、および半固体電極層７と集電体５との間にカーボン層６を有する。半固体電極層７は通常、電極活物質２、導電助剤３および電解液４を含み、かつ流動性を有する層である。図２は半固体電極１′を有して成る従前の二次電池である。半固体電極１′は活物質２′、導電助剤３′、および電解液４′を含む半固体電極層７′ならびに集電体５′を含む。しかしながら、図１とは異なり、図２の従前の二次電池はカーボン層６を有していない。半固体電極１および１′は、半固体の電極層を備える点で、クレイ電極とも称される。尚、導電助剤３は、必ずしも、半固体正極および半固体負極の両方に含まれなければならないというわけではない。例えば、正極および負極の両方がそれぞれ導電助剤３を含んでもよいし、または当該両方が含まなくてもよい。また例えば、正極が導電助剤３を含み、かつ負極が導電助剤３を含まなくてもよい。また例えば、正極が導電助剤３を含まず、かつ負極が導電助剤３を含んでもよい。導電助剤３は通常、少なくとも正極に含まれる。図１は、本発明の一実施態様に係る二次電池の基本的構造の一例を模式的に示した断面図である。 　Hereinafter, the secondary battery of the present invention will be described in detail with reference to the drawings. A secondary battery 10 of the present invention has a semi-solid electrode 1 as shown in FIG. The semi-solid electrode in FIG. 1 schematically shows one of a semi-solid positive electrode or a semi-solid negative electrode. The semisolid electrode 1 has a semisolid electrode layer 7 , a current collector 5 , and a carbon layer 6 between the semisolid electrode layer 7 and the current collector 5 . The semi-solid electrode layer 7 is a layer that normally contains the electrode active material 2, the conductive aid 3 and the electrolytic solution 4 and has fluidity. FIG. 2 shows a conventional secondary battery having a semi-solid electrode 1'. The semi-solid electrode 1' includes a semi-solid electrode layer 7' containing an active material 2', a conductive agent 3', and an electrolytic solution 4', and a current collector 5'. However, unlike FIG. 1 , the conventional secondary battery of FIG. 2 does not have carbon layer 6 . The semi-solid electrodes 1 and 1' are also referred to as clay electrodes in that they comprise semi-solid electrode layers. Incidentally, the conductive aid 3 does not necessarily have to be contained in both the semi-solid positive electrode and the semi-solid negative electrode. For example, both the positive electrode and the negative electrode may each contain the conductive aid 3, or neither of them may contain them. Further, for example, the positive electrode may contain the conductive aid 3 and the negative electrode may not contain the conductive aid 3 . Further, for example, the positive electrode may not contain the conductive aid 3 and the negative electrode may contain the conductive aid 3 . Conductive aid 3 is usually contained at least in the positive electrode. FIG. 1 is a cross-sectional view schematically showing an example of the basic structure of a secondary battery according to one embodiment of the present invention.
　本発明において電極（すなわち正極および負極）の両方は通常、半固体電極である。従って、正極および負極はそれぞれ半固体正極および半固体負極に相当する。換言すると、本発明の二次電池は半固体正極および半固体負極を含み、半固体正極および半固体負極の少なくとも一方が半固体電極に相当する。「半固体電極」とは、その電極層（特にその物質）が固相と液相との混合物であることを意味し、当該混合物は、例えば、スラリー、コロイド懸濁液、エマルジョン、ゲル、またはミセルまたは粒子懸濁液の形態を有していてもよい。従って、半固体電極が有する電極層（すなわち、半固体電極層）は、詳しくは、電極活物質（通常は固相粒子）および電解液（通常は液相）を含むスラリーから構成され、さらに導電助剤（通常は固相粒子）等の添加剤を含んでもよい。このような半固体電極層は、従来のようなバインダー結合型電極層とは異なり、電極活物質同士を結合および／または相互固定するためのバインダーを含有しない。本発明においては、電極（特に電極層）がそのようなバインダーを含有しないことにより、バインダーに起因する電気抵抗の増大を回避することができ、二次電池のさらなる高容量化を達成することができる。本発明において半固体電極（特に半固体電極層）は厳密にバインダーを含有してはならないというわけではない。本発明は、製造過程で電極層に意図せずに混入される不純物としての微量のバインダー、およびカーボン層に含まれる炭素材料を支持するための支持母材の含有を妨げるものではない。そのような観点から、半固体電極（特に半固体電極層）に含有されるバインダーの含有量は、半固体電極層全量に対して、０．１質量％以下、特に０．０１質量％以下であってもよい。バインダーの含有量は、半固体正極層または半固体負極層（特に半固体正極層）のそれぞれにおいて、上記範囲内であればよい。 Both the electrodes (ie, positive and negative electrodes) in the present invention are typically semi-solid electrodes. Accordingly, the positive electrode and the negative electrode correspond to a semi-solid positive electrode and a semi-solid negative electrode, respectively. In other words, the secondary battery of the present invention includes a semi-solid positive electrode and a semi-solid negative electrode, and at least one of the semi-solid positive electrode and the semi-solid negative electrode corresponds to the semi-solid electrode. By "semi-solid electrode" is meant that the electrode layer (particularly the material) is a mixture of solid and liquid phases, such as slurries, colloidal suspensions, emulsions, gels, or It may have the form of micelles or particle suspensions. Therefore, the electrode layer (that is, the semi-solid electrode layer) of the semi-solid electrode is specifically composed of a slurry containing an electrode active material (usually solid phase particles) and an electrolytic solution (usually a liquid phase), and further includes a conductive material. Additives such as auxiliaries (usually solid phase particles) may also be included. Such a semi-solid electrode layer does not contain a binder for binding and/or fixing the electrode active materials together, unlike conventional binder-bonded electrode layers. In the present invention, since the electrode (especially the electrode layer) does not contain such a binder, it is possible to avoid an increase in electrical resistance due to the binder, and to achieve a higher capacity secondary battery. can. In the present invention, the semi-solid electrode (particularly the semi-solid electrode layer) is not strictly prohibited from containing a binder. The present invention does not preclude inclusion of a trace amount of binder as an impurity unintentionally mixed into the electrode layer during the manufacturing process, and a support base material for supporting the carbon material contained in the carbon layer. From such a viewpoint, the content of the binder contained in the semi-solid electrode (especially the semi-solid electrode layer) is 0.1% by mass or less, particularly 0.01% by mass or less, relative to the total amount of the semi-solid electrode layer. There may be. The content of the binder may be within the above range for each of the semi-solid positive electrode layer and the semi-solid negative electrode layer (especially the semi-solid positive electrode layer).
　本発明の一実施形態では、電極活物質、導電助剤および電解液を含む半固体電極層と集電体とを有する半固体電極を含み、半固体電極は、半固体電極層と集電体との間にカーボン層を有する。 An embodiment of the present invention includes a semi-solid electrode having a semi-solid electrode layer comprising an electrode active material, a conductive aid, and an electrolyte, and a current collector, the semi-solid electrode comprising a semi-solid electrode layer and a current collector It has a carbon layer between
　カーボン層とは、炭素材料および炭素材料を支持するための支持母材（以下支持母材と称する）を含む層である。支持母材とは、その母材中に炭素材料を分散させて固定する材料であって、いわゆるバインダーと称される材料に包含される材料であってよい。支持母材として、例えば、ポリマー（例えば、いわゆるプラスチック、またはゴム）等の高分子が用いられる。これらの特徴から、カーボン層は、炭素材料が分散されたポリマー層であってよい。なおカーボン層は、カーボンコート層と称されてもよい。 A carbon layer is a layer containing a carbon material and a supporting base material (hereinafter referred to as a supporting base material) for supporting the carbon material. The supporting base material is a material for dispersing and fixing the carbon material in the base material, and may be a material included in a so-called binder. As a support matrix, for example, a macromolecule such as a polymer (for example, so-called plastic or rubber) is used. Due to these characteristics, the carbon layer may be a polymer layer in which carbon material is dispersed. Note that the carbon layer may also be referred to as a carbon coat layer.
　図１に示すように、カーボン層６は、半固体電極層７と集電体５との間に設けられている。具体的には、カーボン層６は、集電体５の表面に直接的に接するとともに、半固体電極層７とも直接的に接して形成されている。このため、カーボン層６における炭素材料と集電体５との接触頻度が比較的高くなるとともに（図１の８で示す領域）、半固体電極層７とカーボン層６における炭素材料との接触頻度も比較的高くなる。それらの結果として、半固体電極層と集電体５との界面抵抗が比較的低い状態となり、レート特性がより十分に優れるようになる。一方で、従来の二次電池１０′では、図２に示すように、集電体５′と半固体電極層７′における炭素材料との接触頻度が比較的低い（図２の８′で示す領域）。そのため、半固体電極層と集電体との界面抵抗が比較的高い状態となり、レート特性が悪くなる。なお、図１では示されていないが、図１のカーボン層６は支持母材も含む。 As shown in FIG. 1, the carbon layer 6 is provided between the semi-solid electrode layer 7 and the collector 5 . Specifically, the carbon layer 6 is formed in direct contact with the surface of the current collector 5 and also in direct contact with the semi-solid electrode layer 7 . Therefore, the frequency of contact between the carbon material in the carbon layer 6 and the current collector 5 becomes relatively high (the region indicated by 8 in FIG. 1), and the frequency of contact between the semi-solid electrode layer 7 and the carbon material in the carbon layer 6 increases. is also relatively high. As a result, the interfacial resistance between the semi-solid electrode layer and current collector 5 is relatively low, and the rate characteristics are sufficiently excellent. On the other hand, in the conventional secondary battery 10', as shown in FIG. 2, the frequency of contact between the current collector 5' and the carbon material in the semi-solid electrode layer 7' is relatively low (indicated by 8' in FIG. 2). region). As a result, the interfacial resistance between the semi-solid electrode layer and the current collector becomes relatively high, resulting in poor rate characteristics. Although not shown in FIG. 1, the carbon layer 6 of FIG. 1 also includes a support base material.
　炭素材料は、炭素（Ｃ）を主成分とする物質である。炭素材料は、導電性を有するものであればよく、特に制限されるわけではないが、サーマルブラック、ファーネスブラック、チャンネルブラック、ケッチェンブラックおよびアセチレンブラック等のカーボンブラック、黒鉛、カーボンナノチューブおよび気相成長炭素繊維等の炭素繊維などから選択される少なくとも１種を挙げることができる。炭素材料は、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、炭素材料はカーボンブラックを用いることが好ましい。炭素材料の形状に関しては、特に限定されず、球形、板状、繊維状など、どのような形状のものを使用してもよい。 A carbon material is a substance whose main component is carbon (C). The carbon material is not particularly limited as long as it has conductivity, but carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon nanotubes and gas phase At least one selected from carbon fibers such as growing carbon fibers can be mentioned. Carbon black is preferably used as the carbon material from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics. The shape of the carbon material is not particularly limited, and any shape such as spherical, plate-like, and fibrous may be used.
　カーボン層に含まれる炭素材料の含有量は、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、カーボン層全量に対して、好ましくは２０体積％以上６０体積％以下、より好ましくは３０体積％以上５５体積％以下、さらに好ましくは３５体積％以上体積５０％以下、特に好ましくは３５体積％以上４５体積％以下である。上記カーボン層全量とは、カーボン層を構成する各構成要素（例えば、炭素材料および支持母材）の合計含有量を意味する。 From the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics, the content of the carbon material contained in the carbon layer is preferably 20% by volume or more with respect to the total amount of the carbon layer. % by volume or less, more preferably 30% to 55% by volume, more preferably 35% to 50% by volume, particularly preferably 35% to 45% by volume. The total amount of the carbon layer means the total content of each component (for example, the carbon material and the supporting base material) that constitutes the carbon layer.
　カーボン層に含まれる炭素材料の含有量は、例えば、以下の方法により測定された値を用いている。ＳＥＭ観察によるカーボン層の断面画像から、カーボン層の全面積に対するカーボン層に含まれる炭素材料の面積の比率を算出することによって求められる。 For the content of the carbon material contained in the carbon layer, for example, the value measured by the following method is used. It is obtained by calculating the ratio of the area of the carbon material contained in the carbon layer to the total area of the carbon layer from a cross-sectional image of the carbon layer observed by SEM.
　カーボン層に含まれる炭素材料の平均粒径は特に限定されない。例えば、炭素材料の粒径をレーザー回折・散乱法により測定した際、炭素材料の粒径は、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは０．０１μｍ以上５μｍ以下、より好ましくは０．０５μｍ以上４μｍ以下、さらに好ましくは０．１μｍ以上３μｍ以下、特に好ましくは０．１μｍ以上１μｍ以下である。 The average particle diameter of the carbon material contained in the carbon layer is not particularly limited. For example, when the particle size of the carbon material is measured by a laser diffraction/scattering method, the particle size of the carbon material is preferable from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics. is 0.01 μm or more and 5 μm or less, more preferably 0.05 μm or more and 4 μm or less, still more preferably 0.1 μm or more and 3 μm or less, and particularly preferably 0.1 μm or more and 1 μm or less.
　支持母材は、１種または２種以上の高分子を含でもよい。支持母材は、例えば、ポリアクリロニトリル、ポリフッ化ビニリデン、フッ化ビニリデンとヘキサフルオロプロピレンとの共重合体、ポリテトラフルオロエチレン、ポリヘキサフルオロプロピレン、ポリエチレンオキサイド、ポリプロピレンオキサイド、ポリフォスファゼン、ポリシロキサン、ポリ酢酸ビニル、ポリビニルアルコール、ポリメタクリル酸メチル、ポリアクリル酸、ポリメタクリル酸、ＣＭＣ、スチレン－ブタジエンゴム、ニトリル－ブタジエンゴム、ポリスチレンおよび／またはポリカーボネート等の高分子、またはそれらの混合物を挙げることができる。支持母材は、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、ＣＭＣとスチレン－ブタジエンゴムを含むことが好ましい。 The support matrix may contain one or more polymers. The supporting matrix is, for example, polyacrylonitrile, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, Polymers such as polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, CMC, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene and/or polycarbonate, or mixtures thereof may be mentioned. can. The support base material preferably contains CMC and styrene-butadiene rubber from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
　カーボン層に含まれる支持母材の含有量は、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、カーボン層全量に対して、好ましくは３０体積％以上９０体積％以下、より好ましくは４０体積％以上８０体積％以下、さらに好ましくは５０体積％以上７０体積％以下、特に好ましくは５５体積％以上６５体積％以下である。 The content of the supporting base material contained in the carbon layer is preferably 30% by volume or more with respect to the total amount of the carbon layer, from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics. It is 90 volume % or less, more preferably 40 volume % or more and 80 volume % or less, still more preferably 50 volume % or more and 70 volume % or less, and particularly preferably 55 volume % or more and 65 volume % or less.
　カーボン層に含まれる支持母材が２種類以上の高分子を含む場合、カーボン層全量に対する支持母材の含有量は、カーボン層全量に対するそれら２種類以上の高分子の含有量（体積％）の合計値としてよい。支持母材が２種類以上の高分子を含む場合、支持母材に含まれる当該２種以上の高分子のそれぞれの含有量の比率は、特に制限されない。電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、支持母材に含まれる２種類以上の高分子は、それぞれ互いに等量となるように含まれていることが好ましい。 When the supporting matrix contained in the carbon layer contains two or more types of polymers, the content of the supporting matrix relative to the total amount of the carbon layer is the content (% by volume) of the two or more types of polymers relative to the total amount of the carbon layer. It can be a total value. When the supporting base material contains two or more types of polymers, the content ratio of each of the two or more types of polymers contained in the supporting base material is not particularly limited. From the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics, two or more types of polymers contained in the supporting base material are contained in equal amounts. is preferred.
　カーボン層は、半固体電極に含まれる電解液に対して溶けないようになっていてもよい。換言すると、カーボン層に含まれる支持母材は、半固体電極層に含まれる電解液の溶媒に対して溶解性を有さなくてもよい。「溶解性を有さない」とは、例えば２０℃±５で、半固体電極層に含まれる電解液の溶媒１ｍＬあたりに溶解する支持母材が０．００１ｇ以下であることをいう。電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、２０℃±５で、半固体電極層に含まれる電解液の溶媒１ｍＬあたりに溶解する支持母材は、好ましくは０．０００１ｇ以下であり、特に好ましくは０．００００１ｇ以下である。 The carbon layer may be insoluble in the electrolyte contained in the semi-solid electrode. In other words, the supporting base material contained in the carbon layer does not have to be soluble in the solvent of the electrolytic solution contained in the semi-solid electrode layer. "Not soluble" means that 0.001 g or less of the supporting base material dissolves per 1 mL of the solvent of the electrolytic solution contained in the semi-solid electrode layer at 20° C.±5, for example. From the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics, the supporting base material that dissolves per 1 mL of the solvent of the electrolyte contained in the semi-solid electrode layer at 20 ° C. ± 5 is , preferably 0.0001 g or less, particularly preferably 0.00001 g or less.
　カーボン層の厚みは、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは０．１μｍ以上１０μｍ以下、より好ましくは０．３μｍ以上８μｍ以下、さらに好ましくは０．５μｍ以上５μｍ以下、特に好ましくは０．７５μｍ以上２μｍ以下である。カーボン層の厚みは、例えば、断面のＳＥＭ像からの測長によって測定してもよい。 The thickness of the carbon layer is preferably 0.1 μm or more and 10 μm or less, more preferably 0.3 μm or more and 8 μm or less, from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics. It is preferably 0.5 μm or more and 5 μm or less, particularly preferably 0.75 μm or more and 2 μm or less. The thickness of the carbon layer may be measured, for example, by length measurement from a cross-sectional SEM image.
　カーボン層は、半固体電極中に設けられている。具体的には、カーボン層は、半固体電極層と集電体との間に設けられている。換言すると、カーボン層は、集電体上に形成されている。電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、カーボン層は、集電体と密着するように形成されていることが好ましい。 The carbon layer is provided in the semi-solid electrode. Specifically, the carbon layer is provided between the semi-solid electrode layer and the current collector. In other words, the carbon layer is formed on the current collector. From the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics, the carbon layer is preferably formed so as to be in close contact with the current collector.
　半固体正極および半固体負極の少なくとも一方は、上記のカーボン層を有する半固体電極に相当する。詳しくは、カーボン層は、必ずしも、半固体正極または半固体負極の両方に設けられていなければならないというわけはなく、これらの電極のうちの少なくとも一方の電極（特に正極）に設けられていればよい。例えば、正極および負極のそれぞれにカーボン層が設けられていてよい。また例えば、正極にカーボン層が設けられており、かつ負極にカーボン層が設けられていなくてもよい。また例えば、正極にカーボン層が設けられておらず、かつ負極にカーボン層が設けられていてもよい。カーボン層は通常、少なくとも正極に設けられている。例えば、カーボン層が正極に設けられている場合、「半固体電極層」、「集電体」、および「電解液」はそれぞれ、「半固体正極層」、「正極集電体」、および「正極電解液」に相当する。また例えば、カーボン層が負極に設けられている場合、「半固体電極層」、「集電体」、および「電解液」はそれぞれ、「半固体負極層」、「負極集電体」、および「負極電解液」に相当する。 At least one of the semi-solid positive electrode and the semi-solid negative electrode corresponds to the above-described semi-solid electrode having a carbon layer. Specifically, the carbon layer does not necessarily have to be provided on both the semi-solid positive electrode and the semi-solid negative electrode. good. For example, a carbon layer may be provided on each of the positive electrode and the negative electrode. Further, for example, the carbon layer may be provided on the positive electrode and the carbon layer may not be provided on the negative electrode. Further, for example, the carbon layer may not be provided on the positive electrode and the carbon layer may be provided on the negative electrode. A carbon layer is usually provided at least on the positive electrode. For example, when the carbon layer is provided on the positive electrode, the "semi-solid electrode layer", "current collector", and "electrolyte" are respectively "semi-solid positive electrode layer", "positive electrode current collector", and " It corresponds to "positive electrode electrolyte". Further, for example, when the carbon layer is provided on the negative electrode, the “semisolid electrode layer”, the “current collector”, and the “electrolyte” are respectively the “semisolid negative electrode layer”, the “negative electrode current collector”, and the It corresponds to a "negative electrode electrolyte".
　カーボン層を集電体上に設ける方法は特に制限されない。例えば、炭素材料と支持母材を分散させたスラリー（支持母材はスラリー中に溶解しておいてもよい）を集電体上に塗布・乾燥して、カーボン層を集電体上に設けてもよい。スラリーを集電体上に塗布する方法は特に制限されないが、例えば、ドクターブレード法により塗布してもよい。カーボン層は通常、集電体に固定（又は定着）されて形成されている。 The method of providing the carbon layer on the current collector is not particularly limited. For example, a slurry in which a carbon material and a supporting base material are dispersed (the supporting base material may be dissolved in the slurry) is applied on a current collector and dried to form a carbon layer on the current collector. may The method of applying the slurry onto the current collector is not particularly limited, but for example, a doctor blade method may be used. A carbon layer is usually formed by being fixed (or fixed) to a current collector.
　本発明の二次電池では、電極層と集電体との間にカーボン層を有するため、電極層と集電体との界面抵抗を低くできる。したがって、電極層の導電率が低く、電極層と集電体との界面抵抗がより律速となる場合でも、本発明の二次電池は電極層と集電体との界面抵抗が低いため、レート特性の向上が可能である。すなわち、本発明の二次電池が従来の二次電池では十分なレート特性を発揮できないような電極層の導電率を有していても、本発明の二次電池は電極層と集電体との界面抵抗がより低いためレート特性により十分に優れている。換言すると、本発明の二次電池は、電極層の導電率がより低い場合に、従来の二次電池と比較してより十分に優れたレート特性を示す。例えば、本発明の二次電池は、半固体正極層の導電率が５．０×１０－２Ｓ／ｃｍ未満であってもよく、好ましくは３．５×１０－２Ｓ／ｃｍ未満、より好ましくは１．０×１０－２Ｓ／ｃｍ未満、さらに好ましくは０．５×１０－２Ｓ／ｃｍ未満、特に好ましくは０．２５×１０－２Ｓ／ｃｍ未満、格別に好ましくは０．１５×１０－２Ｓ／ｃｍ未満であってよい。例えば、本発明の二次電池は、半固体負極層の導電率が５．０×１０－２Ｓ／ｃｍ未満であってもよく、好ましくは３．５×１０－２Ｓ／ｃｍ未満、より好ましくは１．０×１０－２Ｓ／ｃｍ未満、さらに好ましくは０．５×１０－２Ｓ／ｃｍ未満、特に好ましくは０．２５×１０－２Ｓ／ｃｍ未満、格別に好ましくは０．１５×１０－２Ｓ／ｃｍ未満であってよい。 Since the secondary battery of the present invention has the carbon layer between the electrode layer and the current collector, the interfacial resistance between the electrode layer and the current collector can be reduced. Therefore, even if the electrode layer has a low electrical conductivity and the interfacial resistance between the electrode layer and the current collector is more rate-determining, the secondary battery of the present invention has a low interfacial resistance between the electrode layer and the current collector. It is possible to improve the characteristics. That is, even if the secondary battery of the present invention has the conductivity of the electrode layer such that a conventional secondary battery cannot exhibit sufficient rate characteristics, the secondary battery of the present invention has the electrode layer and the current collector. The rate performance is much better due to the lower interfacial resistance of . In other words, the secondary battery of the present invention exhibits much better rate characteristics than conventional secondary batteries when the conductivity of the electrode layer is lower. For example, in the secondary battery of the present invention, the conductivity of the semisolid positive electrode layer may be less than 5.0×10 −2 S/cm, preferably less than 3.5×10 −2 S/cm, more It is preferably less than 1.0×10 −2 S/cm, more preferably less than 0.5×10 −2 S/cm, particularly preferably less than 0.25×10 −2 S/cm, particularly preferably less than 0.25×10 −2 S/cm. It may be less than 15×10 −2 S/cm. For example, in the secondary battery of the present invention, the conductivity of the semisolid negative electrode layer may be less than 5.0×10 −2 S/cm, preferably less than 3.5×10 −2 S/cm, more It is preferably less than 1.0×10 −2 S/cm, more preferably less than 0.5×10 −2 S/cm, particularly preferably less than 0.25×10 −2 S/cm, particularly preferably less than 0.25×10 −2 S/cm. It may be less than 15×10 −2 S/cm.
　電極層の導電率が低くなると、電極層と集電体との界面抵抗がより律速となり、レート特性の低下がより顕著となる。電極層の導電率は、例えば、以下の方法により測定された値を用いている。ＴＡ　Ｉｎｓｔｒｕｍｅｎｔｓ製のレオメータ（Ｄｉｓｃｏｖｅｒｙ　ＨＲ－１）に誘電測定用治具を取り付け、そこにインピーダンスアナライザＥＣ－Ｌａｂ－ＢＩ－００１を接続することで、電極層の体積抵抗率測定を行い、その逆数を導電率とした。なお、測定はレオメータにてギャップを５００、３００、１００μｍと変化させて１００ｋＨｚで取得した抵抗値とギャップとの傾き（Ω／ｃｍ）に、測定治具プレートの面積（ｃｍ２）を掛け合わせることで求めた。 As the conductivity of the electrode layer becomes lower, the interface resistance between the electrode layer and the current collector becomes more rate-determining, and the drop in rate characteristics becomes more pronounced. For the conductivity of the electrode layer, a value measured by, for example, the following method is used. A dielectric measurement jig is attached to a rheometer (Discovery HR-1) manufactured by TA Instruments, and an impedance analyzer EC-Lab-BI-001 is connected to measure the volume resistivity of the electrode layer. conductivity. In addition, the measurement is performed by multiplying the slope (Ω/cm) between the resistance value and the gap obtained at 100 kHz by changing the gap to 500, 300, and 100 μm with a rheometer by the area (cm 2 ) of the measurement jig plate. I asked for it.
　電極層の導電率は、電極層に含まれる導電助剤の量を調整することにより制御できる。例えば、電極層に含まれる導電助剤の量を少なくすると、電極層の導電率をより低くすることができる。一方で、電極層に含まれる導電助剤の量を多くすると、電極層の導電率をより高くすることができる。 The conductivity of the electrode layer can be controlled by adjusting the amount of conductive aid contained in the electrode layer. For example, the electrical conductivity of the electrode layer can be made lower by reducing the amount of the conductive aid contained in the electrode layer. On the other hand, the electrical conductivity of the electrode layer can be increased by increasing the amount of the conductive aid contained in the electrode layer.
　正極に含まれる正極活物質および負極に含まれる負極活物質は、二次電池において電子の受け渡しに直接関与する物質であり、充放電、すなわち電池反応を担う正負極の主物質である。より具体的には、「正極に含まれる正極活物質」および「負極に含まれる負極活物質」に起因して電解液にイオンがもたらされ、かかるイオンが正極と負極との間で移動して電子の受け渡しが行われて充放電がなされる。このような媒介イオンとしては、充放電が可能な限り特に限定されず、例えば、リチウムイオンまたはナトリウムイオン（特にリチウムイオン）が挙げられる。正極および負極は特にリチウムイオンを吸蔵放出可能な電極であってもよい。つまり、本発明の二次電池は、電解液を介してリチウムイオンが正極活物質と負極活物質との間で移動して電池の充放電が行われる二次電池であってもよい。充放電にリチウムイオンが関与する場合、本発明に係る二次電池は、いわゆる“リチウムイオン電池”に相当する。 The positive electrode active material contained in the positive electrode and the negative electrode active material contained in the negative electrode are substances that are directly involved in the transfer of electrons in the secondary battery, and are the main materials of the positive and negative electrodes that are responsible for charging and discharging, that is, the battery reaction. More specifically, ions are brought to the electrolytic solution due to the “positive electrode active material contained in the positive electrode” and the “negative electrode active material contained in the negative electrode”, and the ions move between the positive electrode and the negative electrode. Electrons are transferred to the battery and charged/discharged. Such mediator ions are not particularly limited as long as they can be charged and discharged, and examples thereof include lithium ions or sodium ions (especially lithium ions). The positive and negative electrodes may in particular be electrodes capable of intercalating and deintercalating lithium ions. That is, the secondary battery of the present invention may be a secondary battery in which charging and discharging are performed by moving lithium ions between the positive electrode active material and the negative electrode active material via the electrolyte. When lithium ions are involved in charging and discharging, the secondary battery according to the present invention corresponds to a so-called "lithium ion battery".
　正極の正極活物質は例えば粒状体から成ることが好ましい。更には、電池反応を推進する電子の伝達を円滑にするために導電助剤が正極（特に正極層）に含まれていることも好ましい。同様にして、負極の負極活物質は例えば粒状体から成ることが好ましく、電池反応を推進する電子の伝達を円滑にするために導電助剤が負極（特に負極層）に含まれていてもよい。このように、複数の成分が含有されて成る形態ゆえ、正極層および負極層はそれぞれ“正極合材層”および“負極合材層”などと称すこともできる。 The positive electrode active material of the positive electrode is preferably made of, for example, granular material. Furthermore, it is also preferable that the positive electrode (especially the positive electrode layer) contains a conductive aid in order to facilitate the transfer of electrons that promote the battery reaction. Similarly, the negative electrode active material of the negative electrode is preferably made of, for example, a granular material, and a conductive aid may be contained in the negative electrode (especially the negative electrode layer) in order to facilitate the transfer of electrons that promote the battery reaction. . Because of such a configuration in which a plurality of components are contained, the positive electrode layer and the negative electrode layer can also be referred to as a "positive electrode mixture layer" and a "negative electrode mixture layer", respectively.
　上記の通り、半固体電極層は電極活物質、導電助剤、および電解液を含む。半固体電極はプレス工程を経ないため、半固体電極層と集電体との界面抵抗をより十分に下げるためには、電極層中に必要以上に多くの導電助剤を添加する必要が生じ得る。導電助剤の量を多くすると、導電助剤は捕液性が高いため半固体電極層に流動性を付与するために必要な電解液量を高めてしまう。電極層中の導電助剤の量を多くし電解液量も高めると、電極層中の活物質の量が相対的により少なくなりエネルギー密度がより低下してしまう。ここでいうエネルギー密度とは、電極層中の活物質比率を意味する。一方で、電極層に含まれる導電助剤の量を少なくすると、半固体電極層に流動性を付与するために必要な電解液量を低める。電極層中の導電助剤の量を少なくし電解液量も低めると、活物質の量が相対的に多くなりエネルギー密度がより増加する。本発明の二次電池はカーボン層を電極層と集電体との間に有することにより、導電助剤の量が比較的少ない場合でも、半固体電極層と集電体との界面抵抗が低く、レート特性により優れる。このため、本発明の二次電池は、より優れたレート特性を維持しつつ、電極層中の導電助剤の量を少なくでき、流動性を付与するために必要な電解液の量も低減することができる。また、本発明の二次電池は、導電助剤と電解液の量を比較的少なくできるため、電極層中の活物質の量を相対的により多くでき、エネルギー密度をより増加できる。 As described above, the semi-solid electrode layer contains an electrode active material, a conductive aid, and an electrolytic solution. Since the semi-solid electrode does not undergo a pressing process, it becomes necessary to add a larger amount of conductive aid than necessary to the electrode layer in order to sufficiently reduce the interfacial resistance between the semi-solid electrode layer and the current collector. obtain. If the amount of the conductive aid is increased, the amount of electrolytic solution required to impart fluidity to the semi-solid electrode layer is increased because the conductive aid has a high liquid trapping property. If the amount of the conductive agent in the electrode layer is increased and the amount of the electrolytic solution is also increased, the amount of active material in the electrode layer is relatively decreased, resulting in a further decrease in energy density. The energy density here means the active material ratio in the electrode layer. On the other hand, if the amount of the conductive additive contained in the electrode layer is reduced, the amount of electrolytic solution required to impart fluidity to the semi-solid electrode layer is reduced. When the amount of the conductive agent in the electrode layer is reduced and the amount of the electrolytic solution is also reduced, the amount of active material is relatively increased and the energy density is further increased. Since the secondary battery of the present invention has a carbon layer between the electrode layer and the collector, the interfacial resistance between the semi-solid electrode layer and the collector is low even when the amount of the conductive aid is relatively small. , better rate characteristics. Therefore, the secondary battery of the present invention can reduce the amount of conductive aid in the electrode layer while maintaining better rate characteristics, and also reduces the amount of electrolytic solution required to impart fluidity. be able to. Also, in the secondary battery of the present invention, since the amounts of the conductive aid and the electrolyte can be relatively reduced, the amount of the active material in the electrode layer can be relatively increased, and the energy density can be further increased.
　正極活物質は、リチウムイオンの吸蔵放出に資する物質であってもよい。かかる観点でいえば、正極活物質は例えばリチウム含有複合酸化物であってもよい。より具体的には、正極活物質は、リチウムと、コバルト、ニッケル、マンガンおよび鉄から成る群から選択される少なくとも１種の遷移金属とを含むリチウム遷移金属複合酸化物であってもよい。つまり、本発明に係る二次電池の正極層においては、そのようなリチウム遷移金属複合酸化物が正極活物質として好ましくは含まれていてもよい。例えば、正極活物質はコバルト酸リチウム、ニッケル酸リチウム、マンガン酸リチウム、リン酸鉄リチウム、または、それらの遷移金属の一部を別の金属で置き換えたものであってよい。このような正極活物質は、単独種として含まれてよいものの、二種以上が組み合わされて含まれていてもよい。より好適な態様では正極（特に正極層）に含まれる正極活物質がコバルト酸リチウムとなっている。 The positive electrode active material may be a material that contributes to absorption and release of lithium ions. From this point of view, the positive electrode active material may be, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material may be a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese and iron. That is, the positive electrode layer of the secondary battery according to the present invention may preferably contain such a lithium-transition metal composite oxide as a positive electrode active material. For example, the positive electrode active material may be lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or a transition metal thereof partially replaced by another metal. Although such a positive electrode active material may be contained as a single species, it may be contained in combination of two or more species. In a more preferred embodiment, the positive electrode active material contained in the positive electrode (especially the positive electrode layer) is lithium cobaltate.
　正極活物質の平均粒径は特に限定されず、例えば、１μｍ以上１００μｍ以下、特に１μｍ以上５０μｍ以下であってもよく、エネルギー密度のさらなる向上、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは１μｍ以上３０μｍ以下、より好ましくは１０μｍ以上２０μｍ以下である。 The average particle size of the positive electrode active material is not particularly limited, and may be, for example, 1 μm or more and 100 μm or less, particularly 1 μm or more and 50 μm or less, further improving the energy density and further reducing the interfacial resistance between the electrode layer and the current collector. , and from the viewpoint of further improving rate characteristics, the thickness is preferably 1 μm or more and 30 μm or less, more preferably 10 μm or more and 20 μm or less.
　正極活物質の平均粒径は、レーザー回折・散乱法により求められる粒度分布において、小粒径側からの積算粒子体積が全粒子体積の５０％に達するときの粒径Ｄ５０である。 The average particle size of the positive electrode active material is the particle size D50 when the cumulative particle volume from the small particle size side reaches 50% of the total particle volume in the particle size distribution determined by the laser diffraction/scattering method.
　正極活物質の含有量は通常、正極層全量に対して、５０質量％以上９０質量％以下であり、エネルギー密度のさらなる向上、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは５５質量％以上９０質量％以下であり、より好ましくは６０質量％以上９０質量％以下であり、さらに好ましくは７０質量％以上９０質量％以下であり、特に好ましくは８０質量％以上９０質量％以下である。上記正極層全量とは、集電体を除く、正極層を構成する各構成要素（例えば、正極活物質、導電助剤、電解液）の合計含有量を意味する。 The content of the positive electrode active material is usually 50% by mass or more and 90% by mass or less with respect to the total amount of the positive electrode layer, and further improves the energy density, further reduces the interfacial resistance between the electrode layer and the current collector, and improves the rate characteristics. From the viewpoint of further improvement, it is preferably 55% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 90% by mass or less, still more preferably 70% by mass or more and 90% by mass or less, and particularly preferably is 80% by mass or more and 90% by mass or less. The total amount of the positive electrode layer means the total content of each component constituting the positive electrode layer (eg, positive electrode active material, conductive aid, electrolytic solution) excluding the current collector.
　正極層における正極活物質の含有量は、例えば、所定量の正極層を計り取り、誘導結合プラズマ質量分析法（ＩＣＰ－ＭＳ）により正極活物質が含有する金属イオン量を定量することで、正極活物質の含有量に変換することによって測定してもよい。 The content of the positive electrode active material in the positive electrode layer is determined, for example, by weighing a predetermined amount of the positive electrode layer and quantifying the amount of metal ions contained in the positive electrode active material by inductively coupled plasma mass spectrometry (ICP-MS). You may measure by converting into content of an active material.
　正極に含まれる得る導電助剤（すなわち正極導電助剤）としては、特に制限されるわけではないが、サーマルブラック、ファーネスブラック、チャンネルブラック、ケッチェンブラックおよびアセチレンブラック等のカーボンブラック、黒鉛、カーボンナノチューブおよび気相成長炭素繊維等の炭素繊維、銅、ニッケル、アルミニウムおよび銀等の金属粉末、ならびに、ポリフェニレン誘導体などから選択される少なくとも１種を挙げることができる。より好適な態様では正極層の導電助剤はカーボンブラックである。さらに好適な態様では、正極層の正極活物質および導電助剤が、コバルト酸リチウムとカーボンブラックとの組合せとなっている。 The conductive aid that can be contained in the positive electrode (that is, the positive electrode conductive aid) is not particularly limited, but includes carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon At least one selected from carbon fibers such as nanotubes and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives. In a more preferred embodiment, the conductive additive in the positive electrode layer is carbon black. In a more preferred embodiment, the positive electrode active material and conductive aid of the positive electrode layer are a combination of lithium cobaltate and carbon black.
　正極（特に正極層）に含まれる導電助剤の平均粒径は特に限定されず、例えば、０．１μｍ以上２０μｍ以下、特に０．１μｍ以上１０μｍ以下であってもよく、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは０．５μｍ以上８μｍ以下、より好ましくは１μｍ以上５μｍ以下である。 The average particle size of the conductive aid contained in the positive electrode (especially the positive electrode layer) is not particularly limited, and may be, for example, 0.1 μm or more and 20 μm or less, particularly 0.1 μm or more and 10 μm or less. From the viewpoint of further reducing the interfacial resistance with and further improving the rate characteristics, the thickness is preferably 0.5 μm or more and 8 μm or less, more preferably 1 μm or more and 5 μm or less.
　正極（特に正極層）に含まれる導電助剤の平均粒径は、レーザー回折・散乱法により求められる粒度分布において、小粒径側からの積算粒子体積が全粒子体積の５０％に達するときの粒径Ｄ５０である。 The average particle size of the conductive additive contained in the positive electrode (especially the positive electrode layer) is the particle size distribution determined by the laser diffraction/scattering method when the cumulative particle volume from the small particle size side reaches 50% of the total particle volume. The particle size is D50.
　正極（特に正極層）に含まれる導電助剤の含有量は通常、正極層全量に対して、０．１質量％以上１０質量％以下であり、エネルギー密度のさらなる向上、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは０．５質量％以上５質量％以下であり、より好ましくは０．５質量％以上３．５質量％以下、特に好ましくは０．５質量％以上２質量％以下である。 The content of the conductive aid contained in the positive electrode (especially the positive electrode layer) is usually 0.1% by mass or more and 10% by mass or less with respect to the total amount of the positive electrode layer, further improving the energy density, the electrode layer and the current collector From the viewpoint of further reducing the interfacial resistance with the It is preferably 0.5% by mass or more and 2% by mass or less.
　正極層における導電助剤の含有量は、例えば、熱重量示差熱分析ＴＧ－ＤＴＡによって測定してもよい。 The content of the conductive aid in the positive electrode layer may be measured, for example, by thermogravimetric differential thermal analysis TG-DTA.
　負極活物質は、リチウムイオンの吸蔵放出に資する物質であってもよい。かかる観点でいえば、負極活物質は例えば各種の炭素材料、酸化物、または、リチウム合金などであってもよい。負極活物質の各種の炭素材料としては、黒鉛（天然黒鉛、人造黒鉛）、ハードカーボン、ソフトカーボン、ダイヤモンド状炭素などを挙げることができる。特に、黒鉛は電子伝導性が高いため好ましい。負極活物質の酸化物としては、酸化シリコン、酸化スズ、酸化インジウム、酸化亜鉛および酸化リチウムなどから成る群から選択される少なくとも１種を挙げることができる。負極活物質のリチウム合金は、リチウムと合金形成され得る金属であればよく、例えば、Ａｌ、Ｓｉ、Ｐｂ、Ｓｎ、Ｉｎ、Ｂｉ、Ａｇ、Ｂａ、Ｃａ、Ｈｇ、Ｐｄ、Ｐｔ、Ｔｅ、Ｚｎ、Ｌａなどの金属とリチウムとの２元、３元またはそれ以上の合金であってよい。このような酸化物は、その構造形態としてアモルファスとなっていることが好ましい。結晶粒界または欠陥といった不均一性に起因する劣化が引き起こされにくくなるからである。より好適な態様では負極の負極活物質が人造黒鉛となっている。 The negative electrode active material may be a material that contributes to intercalation and deintercalation of lithium ions. From this point of view, the negative electrode active material may be, for example, various carbon materials, oxides, or lithium alloys. Examples of various carbon materials for the negative electrode active material include graphite (natural graphite, artificial graphite), hard carbon, soft carbon, diamond-like carbon, and the like. In particular, graphite is preferred because of its high electronic conductivity. As the oxide of the negative electrode active material, at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide and lithium oxide can be used. The lithium alloy of the negative electrode active material may be any metal that can be alloyed with lithium, such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn It may be a binary, ternary or higher alloy of a metal such as La and lithium. Such an oxide is preferably amorphous as its structural form. This is because deterioration due to non-uniformity such as grain boundaries or defects is less likely to occur. In a more preferred embodiment, the negative electrode active material of the negative electrode is artificial graphite.
　負極活物質の平均粒径は特に限定されず、例えば、０．５μｍ以上５０μｍ以下、特に１μｍ以上４０μｍ以下であってもよく、エネルギー密度のさらなる向上、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは２μｍ以上３０μｍ以下、より好ましくは５μｍ以上２０μｍ以下である。 The average particle size of the negative electrode active material is not particularly limited, and may be, for example, 0.5 μm or more and 50 μm or less, particularly 1 μm or more and 40 μm or less. From the viewpoint of further reduction and further improvement of rate characteristics, the thickness is preferably 2 μm or more and 30 μm or less, more preferably 5 μm or more and 20 μm or less.
　負極活物質の平均粒径は、レーザー回折・散乱法により求められる粒度分布において、小粒径側からの積算粒子体積が全粒子体積の５０％に達するときの粒径Ｄ５０である。 The average particle size of the negative electrode active material is the particle size D50 when the cumulative particle volume from the small particle size side reaches 50% of the total particle volume in the particle size distribution obtained by the laser diffraction/scattering method.
　負極活物質の含有量は通常、負極層全量に対して、１０質量％以上９０質量％以下であり、エネルギー密度のさらなる向上をするとともに電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは３０質量％以上９０質量％以下であり、さらに好ましくは５０質量％以上９０質量％以下であり、より好ましくは６０質量％以上９０質量％以下であり、さらに好ましくは７０質量％以上９０質量％以下であり、特に好ましくは８０質量％以上９０質量％以下である。上記負極層全量とは、集電体を除く、負極層を構成する各構成要素（例えば、負極活物質、導電助剤、電解液の合計含有量を意味する。 The content of the negative electrode active material is usually 10% by mass or more and 90% by mass or less with respect to the total amount of the negative electrode layer, further improving the energy density and further reducing the interfacial resistance between the electrode layer and the current collector, and From the viewpoint of further improving rate characteristics, it is preferably 30% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 90% by mass or less, It is more preferably 70% by mass or more and 90% by mass or less, and particularly preferably 80% by mass or more and 90% by mass or less. The total amount of the negative electrode layer means the total content of each component constituting the negative electrode layer (for example, the negative electrode active material, the conductive aid, and the electrolytic solution, excluding the current collector).
　負極に含まれる得る導電助剤（すなわち負極導電助剤）としては、特に制限されるわけではないが、サーマルブラック、ファーネスブラック、チャンネルブラック、ケッチェンブラックおよびアセチレンブラック等のカーボンブラック、カーボンナノチューブおよび気相成長炭素繊維等の炭素繊維、銅、ニッケル、アルミニウムおよび銀等の金属粉末、ならびに、ポリフェニレン誘導体などから選択される少なくとも１種を挙げることができる。 The conductive aid that can be contained in the negative electrode (that is, the negative electrode conductive aid) is not particularly limited, but thermal black, furnace black, channel black, carbon black such as ketjen black and acetylene black, carbon nanotubes and At least one selected from carbon fibers such as vapor-grown carbon fibers, powders of metals such as copper, nickel, aluminum and silver, and polyphenylene derivatives.
　負極（特に負極層）に含まれる導電助剤の平均粒径は特に限定されず、例えば、０．１μｍ以上２０μｍ以下、特に０．１μｍ以上１０μｍ以下であってもよく、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは０．５μｍ以上８μｍ以下、より好ましくは１μｍ以上５μｍ以下である。 The average particle size of the conductive aid contained in the negative electrode (especially the negative electrode layer) is not particularly limited, and may be, for example, 0.1 μm or more and 20 μm or less, particularly 0.1 μm or more and 10 μm or less. From the viewpoint of further reducing the interfacial resistance with and further improving the rate characteristics, the thickness is preferably 0.5 μm or more and 8 μm or less, more preferably 1 μm or more and 5 μm or less.
　負極（特に負極層）に含まれる導電助剤の平均粒径は、レーザー回折・散乱法により求められる粒度分布において、小粒径側からの積算粒子体積が全粒子体積の５０％に達するときの粒径Ｄ５０である。 The average particle size of the conductive aid contained in the negative electrode (especially the negative electrode layer) is the particle size distribution determined by the laser diffraction/scattering method when the cumulative particle volume from the small particle size side reaches 50% of the total particle volume. The particle size is D50.
　負極（特に負極層）に含まれる導電助剤の含有量は通常、負極層全量に対して、０．１質量％以上１０質量％以下であり、エネルギー密度のさらなる向上を電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、好ましくは０．１質量％以上２質量％以下であり、より好ましくは０質量％以上２質量％以下であり、さらに好ましくは０質量％である。負極（特に負極層）に含まれる導電助剤の含有量が０質量％であるとは、当該負極（特に負極層）が導電助剤を含まないということである。 The content of the conductive aid contained in the negative electrode (especially the negative electrode layer) is usually 0.1% by mass or more and 10% by mass or less with respect to the total amount of the negative electrode layer, and further improvement in energy density is achieved by combining the electrode layer and the current collector. From the viewpoint of further reducing the interfacial resistance with and further improving the rate characteristics, it is preferably 0.1% by mass or more and 2% by mass or less, more preferably 0% by mass or more and 2% by mass or less, and still more preferably It is 0% by mass. That the content of the conductive aid contained in the negative electrode (especially the negative electrode layer) is 0% by mass means that the negative electrode (especially the negative electrode layer) does not contain the conductive aid.
　正極に含まれる電解液および負極に含まれる電解液は通常、相互に同一組成の電解液が使用される。 The electrolytic solution contained in the positive electrode and the electrolytic solution contained in the negative electrode usually have the same composition.
　電解液は電極活物質（正極活物質・負極活物質）から放出された金属イオンの移動を助力する。電解液は有機電解液および有機溶媒などの“非水系”の電解液であっても、または水を含む“水系”の電解液であってもよい。本発明の二次電池は、電解液として“非水系”の溶媒と、溶質とを含む電解液が用いられた非水電解液二次電池が好ましい。電解液は液体状またはゲル状などの形態を有し得る（なお、本明細書において“液体状”の非水電解液は「非水電解液」とも称される）。 The electrolyte assists the movement of metal ions released from the electrode active material (positive electrode active material/negative electrode active material). The electrolyte may be a "non-aqueous" electrolyte such as an organic electrolyte and an organic solvent, or an "aqueous" electrolyte containing water. The secondary battery of the present invention is preferably a non-aqueous electrolyte secondary battery in which an electrolytic solution containing a "non-aqueous" solvent and a solute is used as the electrolytic solution. The electrolytic solution may have a form such as liquid or gel (in this specification, the "liquid" non-aqueous electrolytic solution is also referred to as "non-aqueous electrolytic solution").
　具体的な非水電解液の溶媒としては、特に限定されず、少なくともカーボネートを含んで成るものであってもよい。かかるカーボネートは、環状カーボネート類および／または鎖状カーボネート類であってもよい。特に制限されるわけではないが、環状カーボネート類としては、プロピレンカーボネート（ＰＣ）、エチレンカーボネート（ＥＣ）、ブチレンカーボネート（ＢＣ）およびビニレンカーボネート（ＶＣ）から成る群から選択される少なくとも１種を挙げることができる。鎖状カーボネート類としては、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、エチルメチルカーボネート（ＥＭＣ）およびジプロピルカーボネート（ＤＰＣ）から成る群から選択される少なくも１種を挙げることができる。１つの好適な実施態様では、非水電解液として環状カーボネート類と鎖状カーボネート類との組合せが用いられ、例えばエチレンカーボネートとエチルメチルカーボネートとの混合物が用いられる。 A specific solvent for the non-aqueous electrolyte is not particularly limited, and may contain at least carbonate. Such carbonates may be cyclic carbonates and/or linear carbonates. Although not particularly limited, cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC). be able to. Examples of chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC) and dipropyl carbonate (DPC). In one preferred embodiment, a combination of cyclic carbonates and chain carbonates is used as the non-aqueous electrolyte, for example, a mixture of ethylene carbonate and ethylmethyl carbonate is used.
　具体的な非水電解液の溶質としては、例えば、ＬｉＰＦ６およびＬｉＢＦ４などのＬｉ塩が好ましく用いられる。好ましい態様においては、ＬｉＰＦ６である。電解液における溶質の濃度は特に限定されず、例えば、０．１Ｍ以上１０Ｍ以下、特に０．５Ｍ以上３Ｍ以下であってもよい。Ｍはモル／Ｌのことである。 Li salts such as LiPF 6 and LiBF 4 are preferably used as a specific solute of the non-aqueous electrolyte. In a preferred embodiment, it is LiPF6 . The concentration of the solute in the electrolytic solution is not particularly limited, and may be, for example, 0.1M or more and 10M or less, particularly 0.5M or more and 3M or less. M means mol/L.
　半固体電極層における電解液の含有量は、半固体電極層の流動性に影響を与える。例えば、半固体電極における電解液の含有量を多くすると、半固体電極層の流動性がより増加する。一方で、半固体電極における電解液の含有量を少なくすると、半固体電極層の流動性がより減少する。半固体電極層に含まれる電解液の含有量を半固体電極層全量に対して多くすると、半固体電極層に含まれる活物質の含有量が相対的に少なくなり、エネルギー密度がより小さくなる。一方で、半固体電極層に含まれる電解液の含有量を半固体電極層全量に対して少なくすると、半固体電極層に含まれる活物質の含有量が相対的に多くなり、エネルギー密度がより大きくなる。
　正極（特に正極層）および負極（特に負極層）における電解液の含有量は、エネルギー密度のさらなる向上、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、例えば、正極（特に正極層）に含まれる電解液の含有量は通常、正極層全量に対して、好ましくは３０体積％以上７０体積％以下であり、さらに好ましくは３３体積％以上６７体積％以下、より好ましくは４０体積％以上６０体積％以下、特に好ましくは４５体積％以上５５体積％以下であってもよい。また例えば、負極（特に負極層）に含まれる電解液の含有量は通常、負極層全量に対して、好ましくは３０体積％以上７０体積％以下であり、さらに好ましくは３３体積％以上６７体積％以下、より好ましくは４０体積％以上６０体積％以下、特に好ましくは４５体積以上５５体積％以下であってもよい。 The electrolyte content in the semi-solid electrode layer affects the fluidity of the semi-solid electrode layer. For example, increasing the electrolyte content in the semi-solid electrode further increases the fluidity of the semi-solid electrode layer. On the other hand, when the electrolyte content in the semi-solid electrode is reduced, the fluidity of the semi-solid electrode layer is further reduced. When the content of the electrolyte contained in the semi-solid electrode layer is increased with respect to the total amount of the semi-solid electrode layer, the content of the active material contained in the semi-solid electrode layer becomes relatively small, resulting in a smaller energy density. On the other hand, when the content of the electrolyte contained in the semi-solid electrode layer is reduced relative to the total amount of the semi-solid electrode layer, the content of the active material contained in the semi-solid electrode layer is relatively increased, resulting in a higher energy density. growing.
The content of the electrolyte in the positive electrode (especially the positive electrode layer) and the negative electrode (especially the negative electrode layer) is adjusted from the viewpoint of further improving the energy density, further reducing the interfacial resistance between the electrode layer and the current collector, and further improving the rate characteristics. For example, the content of the electrolytic solution contained in the positive electrode (especially the positive electrode layer) is usually preferably 30% by volume or more and 70% by volume or less, more preferably 33% by volume or more and 67% by volume, based on the total amount of the positive electrode layer. Below, more preferably 40% by volume or more and 60% by volume or less, and particularly preferably 45% by volume or more and 55% by volume or less. Further, for example, the content of the electrolytic solution contained in the negative electrode (especially the negative electrode layer) is usually preferably 30% by volume or more and 70% by volume or less, more preferably 33% by volume or more and 67% by volume, based on the total amount of the negative electrode layer. Below, more preferably 40% by volume or more and 60% by volume or less, and particularly preferably 45% by volume or more and 55% by volume or less.
　電極層の厚みは特に限定されず、所望の電池容量に応じて適宜、選択されてもよい。電極層の厚み（特に後述する集電体の１つの主面（片面）あたりの電極層の厚み）は、例えば、本発明の二次電池における片面の電極面積当りの容量が後述の範囲内になるような厚みであり、通常は、８０μｍ以上、特に１５０μｍ以上５００μｍ以下であってもよい。電極層の厚みは正極層の厚みおよび負極層の厚みを包含し、それぞれ独立して選択されてもよい。電極層の厚みは、完成された二次電池における任意の５０箇所における厚みの平均値を用いている。 The thickness of the electrode layer is not particularly limited, and may be appropriately selected according to the desired battery capacity. The thickness of the electrode layer (especially the thickness of the electrode layer per one main surface (single side) of the current collector described later) is such that, for example, the capacity per electrode area of one side in the secondary battery of the present invention is within the range described later. The thickness is usually 80 μm or more, and may be 150 μm or more and 500 μm or less. The thickness of the electrode layer includes the thickness of the positive electrode layer and the thickness of the negative electrode layer, each of which may be independently selected. As the thickness of the electrode layer, an average value of thicknesses at 50 arbitrary locations in the completed secondary battery is used.
　電極（特に半固体電極）は通常、集電体の少なくとも片面（好ましくは両面）に電極層（特に半固体電極層）が設けられる。集電体の構成材料は、導電性を有する限り特に限定されず、例えば、銅、アルミニウムおよびステンレス等から成る群から選択される１種の金属または２種以上の金属を含む合金であってもよい。正極の集電体（すなわち正極集電体）は、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、アルミニウムから構成されていることが好ましい。負極の集電体（すなわち負極集電体）は、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、銅から構成されていることが好ましい。 An electrode (especially a semi-solid electrode) is usually provided with an electrode layer (especially a semi-solid electrode layer) on at least one side (preferably both sides) of a current collector. The constituent material of the current collector is not particularly limited as long as it has conductivity. For example, an alloy containing one metal or two or more metals selected from the group consisting of copper, aluminum, stainless steel, etc. good. The current collector of the positive electrode (that is, the positive electrode current collector) is preferably made of aluminum from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics. The current collector of the negative electrode (that is, the negative electrode current collector) is preferably made of copper from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
　正極および負極の集電体の厚みは特に限定されず、それぞれ独立して、例えば、１μｍ以上３００μｍ以下、特に１μｍ以上１００μｍ以下であってもよい。 The thickness of the current collectors of the positive electrode and the negative electrode is not particularly limited, and may be, for example, 1 μm or more and 300 μm or less, particularly 1 μm or more and 100 μm or less.
　本発明の二次電池は通常、外装体内に封入されている。外装体はフレキシブルパウチ（軟質袋体）であってもよいし、またはハードケース（硬質筐体）であってもよい。外装体は、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、フレキシブルパウチであることが好ましい。 The secondary battery of the present invention is usually enclosed in an outer package. The exterior body may be a flexible pouch (soft bag body) or a hard case (hard housing). The outer package is preferably a flexible pouch from the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics.
　外装体がフレキシブルパウチである場合、フレキシブルパウチは通常、ラミネートフィルムから形成され、周縁部をヒートシールすることにより、シール部を形成する。ラミネートフィルムとしては、金属箔とポリマーフィルムを積層したフィルムが一般的であり、具体的には、外層ポリマーフィルム／金属箔／内層ポリマーフィルムから成る３層構成のものが例示される。外層ポリマーフィルムは水分等の透過および接触等による金属箔の損傷を防止するためのものであり、ポリアミドおよびポリエステル等のポリマーが好適に使用できる。金属箔は水分およびガスの透過を防止するためのものであり、銅、アルミニウム、ステンレス等の箔が好適に使用できる。内層ポリマーフィルムは、内部に収納する電解液から金属箔を保護するとともに、ヒートシール時に溶融封口させるためのものであり、ポリオレフィンまたは酸変性ポリオレフィンが好適に使用できる。ラミネートフィルムの厚みは特に限定されず、例えば、１μｍ以上１ｍｍ以下が好ましい。例えば平面視形状が矩形状である二次電池の場合、外装体は通常、平面視におけるその周縁部でヒートシールされている。詳しくは、外装体が２枚の矩形状を有する外装体材料から構成される場合、外装体は通常、平面視におけるその四辺でヒートシールされている。外装体が１枚の矩形状を有する外装体材料から構成される場合、外装体は通常、平面視におけるその四辺のうち一辺が外装体材料の折り返しにより形成されている。 When the outer packaging is a flexible pouch, the flexible pouch is usually formed from a laminated film, and the periphery is heat-sealed to form a sealed portion. As the laminate film, a film obtained by laminating a metal foil and a polymer film is generally used. Specifically, a three-layer structure composed of an outer layer polymer film/metal foil/inner layer polymer film is exemplified. The outer layer polymer film is intended to prevent permeation of moisture or the like and damage to the metal foil due to contact and the like, and polymers such as polyamide and polyester can be suitably used. The metal foil is for preventing the permeation of moisture and gas, and foils of copper, aluminum, stainless steel, etc. can be suitably used. The inner layer polymer film protects the metal foil from the electrolyte to be housed inside and melts and seals the opening at the time of heat sealing, and polyolefin or acid-modified polyolefin can be suitably used. The thickness of the laminate film is not particularly limited, and is preferably 1 μm or more and 1 mm or less, for example. For example, in the case of a secondary battery having a rectangular shape in plan view, the exterior body is usually heat-sealed at its periphery in plan view. More specifically, when the exterior body is made of two rectangular exterior body materials, the exterior body is usually heat-sealed at its four sides in a plan view. When the exterior body is made of a sheet of exterior body material having a rectangular shape, one of the four sides of the exterior body in a plan view is usually formed by folding the exterior body material.
　外装体がハードケースである場合、ハードケースは通常、金属板から形成され、周縁部をレーザー照射することにより、シール部を形成する。金属板としては、アルミニウム、ニッケル、鉄、銅、ステンレスなどからなる金属材料が一般的である。金属板の厚みは特に限定されず、例えば、１μｍ以上１ｍｍ以下が好ましい。金属板の封止は、周縁部におけるそれらの重なり部分をレーザー照射することにより達成されてもよい。 When the exterior body is a hard case, the hard case is usually made of a metal plate, and the peripheral edge is irradiated with a laser to form a seal. As the metal plate, metal materials such as aluminum, nickel, iron, copper, and stainless steel are generally used. The thickness of the metal plate is not particularly limited, and is preferably 1 μm or more and 1 mm or less, for example. Sealing of the metal plates may be achieved by lasing their overlap at the perimeter.
　本発明の二次電池は高容量化に有効である。電極層は半固体電極層であって、流動性を有するため、その注入量を増やすだけで、電極層の厚みを安定的かつ簡便に増大させることができる。そのような観点から、本発明の二次電池における片面の電極面積当りの容量は好ましくは４ｍＡｈ／ｃｍ２以上であり、より好ましくは５ｍＡｈ／ｃｍ２以上２０ｍＡｈ／ｃｍ２以下である。なお、本発明において電極層は半固体電極層であるため、電極面積当りの容量は、集電体面積当りの容量であってもよい。正極および負極の電極面積当りの容量はそれぞれ独立して上記範囲内であってもよい。集電体の両面に電極層を有する場合、上記電極面積当たりの容量は、片面あたりの容量である。二次電池の電極面積当たりの容量は、例えば、０．２ＣＡ放電によって得られた二次電池の容量を電極面積で割ることで得ることができる。 The secondary battery of the present invention is effective in increasing capacity. Since the electrode layer is a semi-solid electrode layer and has fluidity, the thickness of the electrode layer can be stably and easily increased simply by increasing the injection amount. From such a viewpoint, the capacity per electrode area on one side of the secondary battery of the present invention is preferably 4 mAh/cm 2 or more, more preferably 5 mAh/cm 2 or more and 20 mAh/cm 2 or less. Since the electrode layer is a semi-solid electrode layer in the present invention, the capacity per electrode area may be the capacity per current collector area. The capacity per electrode area of the positive electrode and the negative electrode may be independently within the above range. When the current collector has electrode layers on both sides, the capacity per electrode area is the capacity per one side. The capacity per electrode area of the secondary battery can be obtained, for example, by dividing the capacity of the secondary battery obtained by 0.2 CA discharge by the electrode area.
　本発明の二次電池における電極面積当たりの容量は、電極面積当たりの活物質容量であってよい。電極面積当たりの容量は、例えば、活物質を含むスラリーの電極への注入量を調整にすることによって制御してもよい。具体的には、電極面積当たりの容量は、所定の電極面積当たりの活物質容量となるように、活物質を含むスラリーを電極に注入する量を調整することによって制御してもよい。上記電極面積当たりの容量は、正極および負極の双方の場合を包含しており、正極および負極の面積当たりの容量は、上記制御方法と同様の方法で制御できる。 The capacity per electrode area in the secondary battery of the present invention may be the active material capacity per electrode area. The capacity per electrode area may be controlled, for example, by adjusting the amount of slurry containing the active material injected into the electrode. Specifically, the capacity per electrode area may be controlled by adjusting the amount of slurry containing the active material injected into the electrode so as to achieve a predetermined active material capacity per electrode area. The capacities per electrode area include both positive and negative electrodes, and the capacities per area of the positive and negative electrodes can be controlled in the same manner as the control method described above.
　本発明の二次電池は、外装体の外側表面にさらに保護層（図示せず）を有していてもよい。 The secondary battery of the present invention may further have a protective layer (not shown) on the outer surface of the outer package.
［二次電池の製造方法］
　本発明の二次電池１０は、以下の工程を含む方法により、製造することができる：
　電極活物質、導電助剤および電解液を混合して、電極層用スラリー（すなわち正極層用スラリーおよび負極層用スラリー）を調合する調合工程；
　集電体にカーボン層を形成するカーボン層形成工程；
　カーボン層を有する集電体に電極層用スラリーを塗布し、電極（すなわち正極および負極）を形成する塗布工程；
　電極と電極の間（すなわち正極と負極との間）にセパレータが配置されるように、積層し積層体を作製する積層工程；および
　積層体を外装体に封入する封入工程。 [Method for manufacturing secondary battery]
The secondary battery 10 of the present invention can be manufactured by a method including the following steps:
A preparation step of mixing an electrode active material, a conductive aid, and an electrolytic solution to prepare an electrode layer slurry (that is, a positive electrode layer slurry and a negative electrode layer slurry);
Carbon layer forming step of forming a carbon layer on the current collector;
A coating step of coating an electrode layer slurry on a current collector having a carbon layer to form electrodes (i.e., positive and negative electrodes);
a stacking step of stacking to form a stack such that the separator is disposed between the electrodes (that is, between the positive electrode and the negative electrode); and an encapsulating step of encapsulating the stack in an outer package.
　本発明の二次電池の製造方法は通常、塗布工程の直後に、以下の工程を含んでもよい：
　電極にタブを溶接する溶接工程。 The manufacturing method of the secondary battery of the present invention may usually include the following steps immediately after the coating step:
A welding process that welds a tab to an electrode.
　本発明の二次電池の製造方法はさらに、封入工程の後に、順次、以下の工程を含んでもよい：
　初期充電処理により負極活物質表面に固体電解質界面被膜を形成し、二次電池前駆体を形成する充放電工程；および
　二次電池前駆体をエージングするエージング工程。 The manufacturing method of the secondary battery of the present invention may further include the following steps in sequence after the encapsulation step:
a charging/discharging step of forming a solid electrolyte interfacial coating on the surface of the negative electrode active material by an initial charging treatment to form a secondary battery precursor; and an aging step of aging the secondary battery precursor.
　調合工程において、詳しくは、正極活物質、導電助剤および電解液ならびに所望の添加剤を混合および分散して、正極層用スラリーを調合する。また負極活物質および電解液ならびに所望により導電助剤を混合および分散して、負極層用スラリーを調合する。 In the preparation step, more specifically, the positive electrode active material, conductive aid, electrolytic solution, and desired additives are mixed and dispersed to prepare the positive electrode layer slurry. Also, the negative electrode active material, the electrolytic solution, and optionally the conductive aid are mixed and dispersed to prepare the negative electrode layer slurry.
　カーボン層形成工程において、詳しくは、正極集電体に、炭素材料を分散させた支持母材を正極集電体上に塗布・乾燥して、正極集電体上にカーボン層を形成する。 In the carbon layer forming step, more specifically, a support base material in which a carbon material is dispersed is applied onto the positive electrode current collector and dried to form a carbon layer on the positive electrode current collector.
　塗布工程において、詳しくは、カーボン層を有する正極集電体に正極層用スラリーを塗布し、正極を形成する。また負極集電体に負極層用スラリーを塗布し、負極を形成する。正極および負極の形成においては、それぞれ独立して、電極層用スラリーは集電体の少なくとも一方の面（好ましくは両方の面）に塗布される。 In the coating step, more specifically, the slurry for the positive electrode layer is applied to the positive electrode current collector having the carbon layer to form the positive electrode. Further, the negative electrode layer slurry is applied to the negative electrode current collector to form the negative electrode. In the formation of the positive electrode and the negative electrode, the electrode layer slurry is applied independently to at least one surface (preferably both surfaces) of the current collector.
　次いで、溶接工程を行ってもよい。溶接工程において、詳しくは、正極に正極用タブを溶接する。また負極に負極用タブを溶接する。正極用タブおよび負極用タブを構成する材料は、導電性を有する限り特に限定されず、例えば、集電体の構成材料と同様の材料から選択されてもよい。正極用タブは、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、アルミニウムから構成されていることが好ましい。負極用タブは、電極層と集電体との界面抵抗のさらなる低減、およびレート特性のさらなる向上の観点から、銅から構成されていることが好ましい。溶接工程は塗布工程の前（特に直前）に行ってもよい。 Then, a welding process may be performed. In the welding step, specifically, the positive electrode tab is welded to the positive electrode. Also, a negative electrode tab is welded to the negative electrode. The material constituting the positive electrode tab and the negative electrode tab is not particularly limited as long as it has conductivity, and may be selected from, for example, the same material as the material constituting the current collector. From the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics, the positive electrode tab is preferably made of aluminum. From the viewpoint of further reducing the interfacial resistance between the electrode layer and the current collector and further improving the rate characteristics, the negative electrode tab is preferably made of copper. The welding step may be performed before (particularly immediately before) the coating step.
　積層工程において、詳しくは、正極および負極を、正極と負極とが交互に配置されつつそれらの間にセパレータが配置されるように積層し、積層体を作製する。その後、積層体を外装体材料で挟み込む。挟み込みは、平面視において積層体の最上位と最下位に外装体が配置される限り特に限定されず、例えば、以下の方法（ｉ）または（ｉｉ）により達成されてもよい：
　方法（ｉ）積層体を２枚の外装体材料により挟み込む；
　方法（ｉｉ）予めシールすることにより形成された、平面視において１辺に開口部を有する袋状外装体内に積層体を収容させる。
　方法（ｉ）においては、２枚の外装体材料の代わりに、連続した１枚の外装体材料を折り返して用いてもよい。 Specifically, in the stacking step, the positive electrode and the negative electrode are stacked such that the positive electrode and the negative electrode are alternately arranged and the separator is arranged between them to produce a laminate. After that, the laminate is sandwiched between outer packaging materials. The sandwiching is not particularly limited as long as the exterior bodies are arranged at the top and bottom of the laminate in plan view, and may be achieved, for example, by the following method (i) or (ii):
Method (i) Sandwiching the laminate with two sheets of armor material;
Method (ii) The laminate is housed in a bag-shaped exterior body having an opening on one side in a plan view, which is formed by sealing in advance.
In the method (i), instead of using two sheets of armor material, one continuous sheet of armor material may be folded back.
　封入工程において、詳しくは、外装体材料の周縁部にある重なり部分をシールし、外装体内部を真空にする。上記挟み込み工程において、方法（ｉ）を採用する場合、外装体材料の周縁部をそれらの重なり部分でシールしつつ、外装体内部を真空状態にする。方法（ｉｉ）を採用する場合、袋状外装体の開口部をそれらの重なり部分でシールしつつ、外装体内部を真空状態にする。なお、重なり部分とは、外装体材料同士の重なり部分である。 In the encapsulation process, in detail, the overlapped portion at the peripheral edge of the exterior material is sealed, and the interior of the exterior is evacuated. When the method (i) is employed in the sandwiching step, the inside of the exterior body is evacuated while sealing the peripheral edges of the exterior body material at their overlapped portions. When method (ii) is employed, the opening of the bag-shaped outer package is sealed by the overlapped portion thereof, and the inside of the outer package is evacuated. Note that the overlapping portion is the overlapping portion of the exterior body materials.
　続いて、充放電工程およびエージング工程を行ってもよい。
　充放電工程において、詳しくは初期充電処理により負極活物質表面に固体電解質界面（Solid Electrolyte Interface）被膜（以下、「ＳＥＩ被膜」という）を形成する。 Subsequently, a charge/discharge step and an aging step may be performed.
In the charging/discharging step, more specifically, a solid electrolyte interface coating (hereinafter referred to as “SEI coating”) is formed on the surface of the negative electrode active material by an initial charging process.
　初期充電処理は、負極活物質表面にＳＥＩ被膜を形成することを目的として行われる最初の充電処理であり、コンディショニング処理またはフォーメーション処理とも呼ばれる。ＳＥＩ被膜は、本処理において電解液に含まれる添加剤が負極活物質表面で還元分解することにより形成され、二次電池としての使用時における負極活物質表面での当該添加剤のさらなる分解を防止する。ＳＥＩ被膜は通常、ＬｉＦ、Ｌｉ２ＣＯ３、ＬｉＯＨおよびＬｉＯＣＯＯＲ（Ｒは１価有機基、例えば、アルキル基を示す）からなる群から選択される１種以上の物質を含む。このようなＳＥＩ被膜が負極活物質表面により均一に形成されることにより、二次電池において電解液成分の分解が防止され、二次電池の容量安定化および長寿命化を達成することができる。 The initial charging treatment is the initial charging treatment for the purpose of forming an SEI film on the surface of the negative electrode active material, and is also called conditioning treatment or formation treatment. The SEI coating is formed by reductive decomposition of the additive contained in the electrolytic solution on the surface of the negative electrode active material in this treatment, and prevents further decomposition of the additive on the surface of the negative electrode active material during use as a secondary battery. do. SEI coatings typically contain one or more materials selected from the group consisting of LiF, Li2CO3 , LiOH and LiOCOOR, where R represents a monovalent organic group, such as an alkyl group. By uniformly forming such an SEI coating on the surface of the negative electrode active material, the decomposition of the electrolytic solution components in the secondary battery is prevented, and the capacity stabilization and longevity of the secondary battery can be achieved.
　初期充電処理では、充電を少なくとも１回行えばよい。通常は１回以上の充放電を行う。１回の充放電は、１回の充電およびその後の１回の放電を含む。充放電を２回以上行う場合、充電－放電を当該回数だけ繰り返す。本処理で行われる充放電の回数は通常、１回以上３回以下である。 In the initial charging process, charging should be performed at least once. Normally, charging and discharging are performed one or more times. One charge/discharge includes one charge and one subsequent discharge. When charging/discharging is performed two or more times, charging/discharging is repeated that number of times. The number of times of charge/discharge performed in this process is usually 1 or more and 3 or less.
　充電方法は、定電流充電方法または定電圧充電方法であっても、またはこれらの組み合わせであってもよい。例えば、一度の充電の間に定電圧充電と定電圧充電を繰り返してもよい。充電条件は、ＳＥＩ被膜が形成される限り特に限定されない。ＳＥＩ被膜の厚みの均一性のさらなる向上の観点からは、定電流充電を行った後、定電圧充電を行うことが好ましい。 The charging method may be a constant current charging method, a constant voltage charging method, or a combination thereof. For example, constant voltage charging and constant voltage charging may be repeated during one charge. Charging conditions are not particularly limited as long as the SEI film is formed. From the viewpoint of further improving the uniformity of the thickness of the SEI film, it is preferable to perform constant voltage charging after performing constant current charging.
　放電方法は通常、定電流放電方法または定電圧放電方法であっても、またはこれらの組み合わせであってもよい。放電条件は、ＳＥＩ被膜が形成される限り特に限定されない。ＳＥＩ被膜の厚みの均一性のさらなる向上の観点からは、定電流放電を行うことが好ましい。 The discharge method may generally be a constant current discharge method, a constant voltage discharge method, or a combination thereof. Discharge conditions are not particularly limited as long as the SEI coating is formed. From the viewpoint of further improving the uniformity of the thickness of the SEI coating, constant current discharge is preferably performed.
　初期充電処理において二次電池は通常、２５℃以上１００℃以下の範囲内の温度に維持され、好ましくは３５℃以上９０℃以下の範囲内、より好ましくは４０℃以上８５℃以下の温度に維持される。 In the initial charging process, the secondary battery is usually maintained at a temperature within the range of 25° C. or higher and 100° C. or lower, preferably 35° C. or higher and 90° C. or lower, more preferably 40° C. or higher and 85° C. or lower. be done.
　エージング工程において、詳しくは、安定化処理によりＳＥＩ被膜を安定化させる。ＳＥＩ被膜の安定化処理は、初期充電処理後の二次電池を開回路状態で放置することでＳＥＩ被膜を安定化させる処理である。 In the aging process, in detail, the SEI coating is stabilized by a stabilization treatment. The SEI coating stabilization process is a process for stabilizing the SEI coating by leaving the secondary battery in an open circuit state after the initial charging process.
　安定化処理において二次電池の温度は特に限定されず、例えば１５℃以上８０℃以下の範囲内に維持されてもよい。二次電池は、ＳＥＩ被膜のさらなる安定化の観点から２０℃以上７５℃以下の範囲内の温度に維持されることが好ましく、より好ましくは２５℃以上７０℃以下の温度に維持される。詳しくは、二次電池を一定温度に設定された空間に放置することで温度を上記範囲内に維持することができる。 The temperature of the secondary battery in the stabilization process is not particularly limited, and may be maintained, for example, within the range of 15°C or higher and 80°C or lower. From the viewpoint of further stabilizing the SEI coating, the secondary battery is preferably maintained at a temperature within the range of 20° C. or higher and 75° C. or lower, and more preferably maintained at a temperature of 25° C. or higher and 70° C. or lower. Specifically, the temperature can be maintained within the above range by leaving the secondary battery in a space set to a constant temperature.
　安定化処理において放置時間はＳＥＩ被膜の安定化が促進される限り特に限定されず、通常は１０分以上３０日以下であり、上記ＳＥＩ被膜のさらなる安定化の観点から好ましくは３０分以上１４日以下の範囲内であり、より好ましくは１時間以上７日以下の範囲内である。 In the stabilization treatment, the standing time is not particularly limited as long as the stabilization of the SEI coating is promoted, and is usually 10 minutes or more and 30 days or less, and from the viewpoint of further stabilization of the SEI coating, preferably 30 minutes or more and 14 days. It is within the following range, and more preferably within the range of 1 hour or more and 7 days or less.
　本発明に係る二次電池の製造方法は、電極製造工程として、調合工程、カーボン層形成工程、および塗布工程を含むのみであり、また組み立て工程として、溶接工程、積層工程、封入工程、充放電工程およびエージング工程を含むのみである。 The manufacturing method of the secondary battery according to the present invention includes only the preparation step, the carbon layer forming step, and the coating step as the electrode manufacturing steps, and the welding step, the laminating step, the encapsulating step, and the charging/discharging step as the assembling steps. It only includes a process and an aging process.
　一方、従来のようなバインダー結合型電極層を含む二次電池の製造方法は、電極製造工程として、電極層形成用塗工液を調合する調合工程；電極層形成用塗工液を集電体に塗工する塗工工程；塗工された電極層形成用塗工液を乾燥させる乾燥工程；電極層を圧密化するプレス工程；電極を所望幅にカットするスリット工程；および所望幅にカットされた電極を所望の形状・寸法に裁断して電極とする裁断工程を含み、組み立て工程として、電極にタブを溶接する溶接工程；電極を、当該電極を構成する正極と負極とが交互に配置されつつそれらの間にセパレータが配置されるように積層して積層体を作製する積層工程；作製した積層体を外装体内に挟み込み、その外装体に、電解液を注入する注液工程；電解液を電極に真空下で含浸させる含浸工程；および積層体を外装体に封入する封入工程；初期充電処理により負極活物質表面に固体電解質界面被膜を形成し、二次電池前駆体を形成する充放電工程；および二次電池前駆体をエージングするエージング工程を含む。
　従って、本発明に係る二次電池の製造方法は、電極製造工程および組み立て工程が共に非常に簡略化され、劇的な設備投資抑制および製造プロセスコストの削減を達成することができる。 On the other hand, the manufacturing method of a secondary battery including a conventional binder-bonded electrode layer includes, as an electrode manufacturing process, a preparation step of preparing an electrode layer-forming coating solution; A coating step of coating on; a drying step of drying the coated electrode layer forming coating solution; a pressing step of consolidating the electrode layer; a slitting step of cutting the electrode to a desired width; The electrode is cut into a desired shape and size to form an electrode, and the assembly process includes a welding process in which a tab is welded to the electrode; A lamination step of laminating the laminate so that a separator is arranged between them to produce a laminate; An injection step of sandwiching the produced laminate in an outer package and injecting an electrolytic solution into the outer package; An impregnation step of impregnating the electrode under vacuum; and an encapsulation step of enclosing the laminate in an outer package; a charging and discharging step of forming a secondary battery precursor by forming a solid electrolyte interfacial coating on the surface of the negative electrode active material by initial charging treatment. and an aging step of aging the secondary battery precursor.
Therefore, in the secondary battery manufacturing method according to the present invention, both the electrode manufacturing process and the assembling process are greatly simplified, and a dramatic reduction in equipment investment and manufacturing process costs can be achieved.
＜二次電池の製造＞
（実施例１：半固体電極型二次電池）
　正極作製
　正極層スラリーを塗布するＡｌ箔の表面に、１μｍ厚のカーボン層（組成：カーボンブラック：ＣＭＣ：ＳＢＲ＝４０：３０：３０（ｖｏｌ％））を予め形成させた。詳しくは、Ａｌ箔表面のカーボン層は、カーボンブラック平均粒径０．６μｍ、ＣＭＣ、およびＳＢＲを４０：３０：３０（ｖｏｌ％）となるように水中に分散させたものを、ダイコーターを用いてＡｌ箔の表面に厚さ１μｍとなるように塗布・乾燥させることで得た。
　正極活物質として平均粒径１５μｍのコバルト酸リチウム（ＬＣＯ）を、導電助剤として平均粒径２．８μｍのカーボンブラックを、電解液として１ＭでＬｉＰＦ６を混合溶媒（ＥＣ：ＥＭＣ＝２５：７５ｖｏｌ）に溶解させてなる溶液を、重量比で６８：３：２９となるように調合・分散処理し、流動性のある正極層スラリーを得た。
正極層スラリーを片面の正極活物質容量が５．０ｍＡｈ／ｃｍ２となるように１μｍ厚のカーボン層（組成：カーボンブラック：ＣＭＣ：ＳＢＲ＝４０：３０：３０（ｖｏｌ％））を有する１５μｍ厚のＡｌ箔の片面にドクターブレード法により１０．０ｃｍ×１０．０ｃｍに塗布し、正極を得た。 <Production of secondary battery>
(Example 1: Semi-solid electrode type secondary battery)
A 1 μm-thick carbon layer (composition: carbon black:CMC:SBR=40:30:30 (vol %)) was previously formed on the surface of the Al foil on which the positive electrode layer slurry was applied. Specifically, the carbon layer on the surface of the Al foil was prepared by dispersing carbon black with an average particle size of 0.6 μm, CMC, and SBR at 40:30:30 (vol%) in water using a die coater. It was obtained by coating and drying the surface of Al foil so as to have a thickness of 1 μm.
Lithium cobaltate (LCO) with an average particle size of 15 μm as a positive electrode active material, carbon black with an average particle size of 2.8 μm as a conductive agent, and LiPF 6 at 1 M as an electrolyte mixed solvent (EC: EMC = 25: 75 vol. ) was mixed and dispersed in a weight ratio of 68:3:29 to obtain a fluid positive electrode layer slurry.
The positive electrode layer slurry is 15 μm thick with a 1 μm thick carbon layer (composition: carbon black: CMC: SBR = 40:30:30 (vol%)) so that the positive electrode active material capacity on one side is 5.0 mAh / cm 2 10.0 cm×10.0 cm by doctor blade method to obtain a positive electrode.
　負極作製
　負極活物質として平均粒径１０．２μｍの人造黒鉛を、電解液として１ＭでＬｉＰＦ６を混合溶媒（ＥＣ：ＥＭＣ＝２５：７５ｖｏｌ）に溶解してなる溶液を、重量比で６０．０：４０．０となるように調合・分散処理し、流動性のある負極層スラリーを得た。負極層スラリーを片面の負極活物質容量が５．４ｍＡｈ／ｃｍ２となるように１２μｍ厚Ｃｕ箔の片面にドクターブレード法により１０．２ｃｍ×１０．２ｃｍに塗布し、負極を得た。 A solution obtained by dissolving artificial graphite with an average particle size of 10.2 μm as the negative electrode active material and LiPF 6 at 1 M in a mixed solvent (EC: EMC = 25: 75 vol) as the electrolyte solution, at a weight ratio of 60.0. : 40.0 to obtain a fluid negative electrode layer slurry. The negative electrode layer slurry was applied to one side of a 12 μm thick Cu foil by a doctor blade method to obtain a negative electrode of 10.2 cm×10.2 cm so that the negative electrode active material capacity on one side was 5.4 mAh/cm 2 .
　二次電池作製
　タブ溶接した正極と負極を、セパレータを介して互いに張り合わせ、アルミラミネートで挟み、真空シールを行った。０．２ＣＡで充放電を行った後、ＳＯＣ７０％まで充電し、５５℃で２４時間のエージング処理を行い、容量約５００ｍＡｈの二次電池を完成させた。半固体正極において、バインダーの含有量は、本実施例で完成した二次電池内における半固体正極層全量に対して、０．０１以下質量％であった。半固体負極において、バインダーの含有量は、本実施例で完成した二次電池内における半固体負極層全量に対して、０．０１以下質量％であった。 Preparation of secondary battery The tab-welded positive electrode and negative electrode were attached to each other with a separator interposed therebetween, sandwiched between aluminum laminates, and vacuum-sealed. After charging and discharging at 0.2 CA, the battery was charged to SOC 70% and subjected to aging treatment at 55° C. for 24 hours to complete a secondary battery with a capacity of about 500 mAh. In the semi-solid positive electrode, the content of the binder was 0.01% by mass or less with respect to the total amount of the semi-solid positive electrode layer in the secondary battery completed in this example. In the semi-solid negative electrode, the binder content was 0.01% by mass or less with respect to the total amount of the semi-solid negative electrode layer in the secondary battery completed in this example.
（実施例２：半固体電極型二次電池）
　正極作製に際し、正極活物質として平均粒径１５μｍのコバルト酸リチウム（ＬＣＯ）を、導電助剤として平均粒径２．８μｍのカーボンブラックを、電解液として１ＭでＬｉＰＦ６を混合溶媒（ＥＣ：ＥＭＣ＝２５：７５ｖｏｌ）に溶解させてなる溶液を、重量比で８１：１：１８となるように調合・分散処理し、流動性のある正極層スラリーを得たこと以外、実施例１と同様の方法により、二次電池を得た。 (Example 2: Semi-solid electrode type secondary battery)
When producing the positive electrode, lithium cobalt oxide (LCO) with an average particle size of 15 μm as a positive electrode active material, carbon black with an average particle size of 2.8 μm as a conductive agent, and 1 M LiPF 6 as an electrolyte mixed solvent (EC: EMC = 25:75 vol) was prepared and dispersed in a weight ratio of 81:1:18 to obtain a fluid positive electrode layer slurry. A secondary battery was obtained by the method.
（参考例：バインダー結合電極型二次電池）
　正極作製
　正極活物質として平均粒径１５μｍのコバルト酸リチウム（ＬＣＯ）を、導電助剤として平均粒径１μｍのカーボンブラックを、バインダーとしてＰＶｄＦを重量比で９６：２：２となるように、ＮＭＰ中に分散させて正極スラリーを得た。次いで、ダイコーターを用いて片面の活物質容量が５．０ｍＡｈ／ｃｍ２となるように１５μｍ厚のＡｌ箔の片面に塗布・乾燥した後、ロールプレス機を用いて空隙率が１８％となるように圧密化し、スリット・切断して１０．０ｃｍ×１０．０ｃｍの正極を得た。 (Reference example: Binder bonded electrode type secondary battery)
Lithium cobaltate (LCO) with an average particle size of 15 μm as a positive electrode active material, carbon black with an average particle size of 1 μm as a conductive agent, and PVdF as a binder were mixed in NMP at a weight ratio of 96:2:2. to obtain a positive electrode slurry. Next, using a die coater, apply and dry one side of a 15 μm thick Al foil so that the active material capacity on one side becomes 5.0 mAh/cm 2 , and then use a roll press to make the porosity 18%. Then, it was slit and cut to obtain a positive electrode of 10.0 cm×10.0 cm.
　負極作製
　負極活物質として平均粒径１０μｍの人造黒鉛を、導電助剤として平均粒径３μｍの鱗片状黒鉛を、バインダーとしてＣＭＣおよびＳＢＲを重量比で９６：１：３（１．５＋１．５）となるように、水中に分散させて負極スラリーを得た。次いで、ダイコーターを用いて片面の活物質容量が５．４ｍＡｈ／ｃｍ２となるように１２μｍ厚Ｃｕ箔の片面に塗布・乾燥した後、ロールプレス機を用いて空隙率が２３％となるように圧密化し、スリット・切断して１０．２ｃｍ×１０．２ｃｍの負極を得た。 Negative electrode preparation Artificial graphite with an average particle size of 10 μm as a negative electrode active material, flake graphite with an average particle size of 3 μm as a conductive aid, and CMC and SBR as binders at a weight ratio of 96: 1: 3 (1.5 + 1.5) was dispersed in water to obtain a negative electrode slurry. Then, using a die coater, apply and dry one side of a 12 μm thick Cu foil so that the active material capacity on one side becomes 5.4 mAh / cm 2 , and then use a roll press machine so that the porosity becomes 23%. , and slit and cut to obtain a negative electrode of 10.2 cm x 10.2 cm.
　二次電池作製
　タブ溶接した正極と負極を、セパレータを介して互いに張り合わせ、アルミラミネートで挟み、電解液１ＭでＬｉＰＦ６を混合溶媒（ＥＣ：ＥＭＣ＝２５：７５ｖｏｌ）に溶解させてなる溶液を注液し、真空含浸した後、真空シールを行った。０．２ＣＡで充放電を行った後、ＳＯＣ７０％まで充電し、５５℃で２４ｈｒのエージング処理を行い、容量約５００ｍＡｈの二次電池を完成させた。
　正極において、バインダーの含有量は、本実施例で完成した二次電池内における正極層全量に対して、２質量％であった。 Secondary battery production The tab-welded positive electrode and negative electrode are attached to each other through a separator, sandwiched between aluminum laminates, and a solution of LiPF 6 dissolved in a mixed solvent (EC: EMC = 25: 75 vol) with an electrolytic solution of 1 M is poured. After liquidizing and vacuum impregnation, vacuum sealing was performed. After charging and discharging at 0.2 CA, the battery was charged to SOC 70% and subjected to aging treatment at 55° C. for 24 hours to complete a secondary battery with a capacity of about 500 mAh.
In the positive electrode, the content of the binder was 2% by mass with respect to the total amount of the positive electrode layer in the secondary battery completed in this example.
（比較例１：半固体電極型二次電池）
　正極作製に際し、正極層スラリーを塗布するＡｌ箔として、カーボン層を有しない１５μｍ厚の通常Ａｌ箔を用いたこと以外、実施例１と同様の方法により、二次電池を得た。 (Comparative Example 1: Semi-solid electrode type secondary battery)
A secondary battery was obtained in the same manner as in Example 1, except that a normal Al foil having a thickness of 15 μm without a carbon layer was used as the Al foil to which the positive electrode layer slurry was applied in the production of the positive electrode.
（比較例２：半固体電極型二次電池）
　正極作製に際し、正極層スラリーを塗布するＡｌ箔として、カーボン層を有しない１５μｍ厚の通常Ａｌ箔を用いたこと以外、実施例２と同様の方法により、二次電池を得た。 (Comparative Example 2: Semi-solid electrode type secondary battery)
A secondary battery was obtained in the same manner as in Example 2, except that a normal Al foil having a thickness of 15 μm without a carbon layer was used as the Al foil to which the positive electrode layer slurry was applied in the production of the positive electrode.
（電極層の導電率）
　完成した試料に対し、前記方法と同様の方法によって体積抵抗率測定を行い、その逆数を取ることによって電極層の導電率を測定した。 (Conductivity of electrode layer)
The completed sample was subjected to volume resistivity measurement in the same manner as described above, and the conductivity of the electrode layer was measured by taking the reciprocal of the volume resistivity measurement.
（レート特性）
　完成した各種二次電池を２５℃にて２ＣＡで放電した時の容量維持率Ｘ（０．２ＣＡ放電容量比）を測定した。
◎；８５％＜Ｘ（最良）；
〇；７０％＜Ｘ≦８５％（良）；
△；５０％＜Ｘ≦７０％（実用上問題なし）；
×；Ｘ≦５０％（実用上問題あり）。 (rate characteristics)
The capacity retention rate X (0.2 CA discharge capacity ratio) was measured when various completed secondary batteries were discharged at 25° C. and 2 CA.
◎; 85% < X (best);
○; 70% < X ≤ 85% (good);
Δ; 50% < X ≤ 70% (no practical problem);
x; X≤50% (practically problematic).
（カーボン層によるレート特性の上昇度）
実施例１：（実施例１の容量維持率Ｘ）／（比較例１の容量維持率Ｘ）
実施例２：（実施例２の容量維持率Ｘ）／（比較例２の容量維持率Ｘ） (Increase in rate characteristics due to carbon layer)
Example 1: (Capacity retention rate X of Example 1)/(Capacity retention rate X of Comparative example 1)
Example 2: (Capacity retention rate X of Example 2)/(Capacity retention rate X of Comparative example 2)
　各種評価水準および評価結果を表１に示す。 Various evaluation standards and evaluation results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１中の記号は以下の通りである。
※１：調合、塗工、乾燥、プレス、スリット、裁断
※２：タブ溶接、積層体作製、注液、真空含浸、封入、充放電、エージング
※３：調合、カーボン層形成、塗布
※４：タブ溶接、積層体作製、封入、充放電、エージング Symbols in Table 1 are as follows.
*1: Blending, coating, drying, pressing, slitting, cutting *2: Tab welding, laminate fabrication, injection, vacuum impregnation, sealing, charge/discharge, aging *3: Blending, carbon layer formation, coating *4: Tab welding, laminate fabrication, encapsulation, charging/discharging, aging
　全ての実施例および比較例では５．０ｍＡｈ／ｃｍ２という非常に目付が大きい領域で二次電池の作製を行っている。このため、バインダーを含む通常の方法で作製した比較例１では抵抗が高く、レート特性およびサイクル特性が低い結果となっている。 In all the examples and comparative examples, the secondary batteries were manufactured in a very large area of 5.0 mAh/cm 2 . For this reason, in Comparative Example 1, which was produced by a normal method including a binder, the resistance was high, and the rate characteristics and cycle characteristics were low.
　バインダーを含まず流動性のある電極を用いた比較例１では、二次電池製造工程を著しく簡略化でき、２ＣＡ容量維持率を改善できているものの、カーボン層が無い。このため、Ａｌ箔との界面抵抗が高いため、レート特性は低い。 In Comparative Example 1, which uses a fluid electrode that does not contain a binder, the secondary battery manufacturing process can be significantly simplified and the 2CA capacity retention rate can be improved, but there is no carbon layer. Therefore, the interface resistance with the Al foil is high, and the rate characteristic is low.
　カーボン層を有するＡｌ箔を使用した実施例１では、レート特性を高めることができている。 In Example 1, which uses an Al foil having a carbon layer, rate characteristics can be improved.
　また比較例２では、正極電極層中の導電助剤添加量がさらに少なくなり、電極層中の活物質比率（エネルギー密度）を高めることができているものの、電極層の導電率が閾値：１．０×１０－２Ｓ／ｃｍを下回っているため、比較例１と比べると容量維持率の低下が顕著になっている。 In Comparative Example 2, the amount of conductive aid added to the positive electrode layer was further reduced, and although the active material ratio (energy density) in the electrode layer could be increased, the electrical conductivity of the electrode layer was a threshold value of 1. 0×10 −2 S/cm, the decrease in the capacity retention ratio is remarkable compared to Comparative Example 1.
　実施例２では、導電助剤添加量が少なく、合材中の活物質比率を高くできていると同時に、カーボン層を有するＡｌ箔を使用しているため、高いレベルのレート特性が得られている。 In Example 2, the addition amount of the conductive aid is small, and the ratio of the active material in the mixture is high, and at the same time, the Al foil having the carbon layer is used, so a high level of rate characteristics is obtained. there is
　実施例１のレート特性は、比較例１のレート特性と比べて、約１．８倍となっている。実施例２のレート特性は、比較例２のレート特性と比べて、約５．１倍となっている。電極層の導電率が１．０×１０－２Ｓ／ｃｍよりも低い場合に、電極層と集電体との界面の抵抗がより律速になってくる。そのため、１．０×１０－２Ｓ／ｃｍのような導電率の領域で、カーボン層の効果が大きくなる。 The rate characteristic of Example 1 is about 1.8 times as large as the rate characteristic of Comparative Example 1. FIG. The rate characteristic of Example 2 is about 5.1 times as large as the rate characteristic of Comparative Example 2. FIG. When the conductivity of the electrode layer is lower than 1.0×10 −2 S/cm, the resistance at the interface between the electrode layer and the current collector becomes more rate-determining. Therefore, the effect of the carbon layer increases in the conductivity range of 1.0×10 −2 S/cm.
　本発明の二次電池は、電池使用または蓄電が想定される様々な分野に利用することができる。あくまでも例示にすぎないが、本発明の二次電池は、エレクトロニクス実装分野で用いることができる。本発明の一実施形態に係る二次電池はまた、モバイル機器等が使用される電気・情報・通信分野（例えば、携帯電話、スマートフォン、スマートウォッチ、ノートパソコン、デジタルカメラ、活動量計、アームコンピューター、電子ペーパー、ウェアラブルデバイス、ＲＦＩＤタグ、カード型電子マネー、スマートウォッチなどの小型電子機などを含む電気・電子機器分野あるいはモバイル機器分野）、家庭・小型産業用途（例えば、電動工具、ゴルフカート、家庭用・介護用・産業用ロボットの分野）、大型産業用途（例えば、フォークリフト、エレベーター、湾港クレーンの分野）、交通システム分野（例えば、ハイブリッド車、電気自動車、バス、電車、電動アシスト自転車、電動二輪車等の分野）、電力系統用途（例えば、各種発電、ロードコンディショナー、スマートグリッド、一般家庭設置型蓄電システム等の分野）、医療用途（イヤホン補聴器などの医療用機器分野）、医薬用途（服用管理システムなどの分野）、ＩｏＴ分野、ならびに、宇宙・深海用途（例えば、宇宙探査機、潜水調査船等の分野）などに利用することができる。 The secondary battery of the present invention can be used in various fields where battery use or power storage is assumed. Although merely an example, the secondary battery of the present invention can be used in the electronics packaging field. The secondary battery according to one embodiment of the present invention is also used in the electric, information, and communication fields where mobile devices are used (for example, mobile phones, smartphones, smart watches, laptops, digital cameras, activity meters, arm computers, etc.). , electronic paper, wearable devices, RFID tags, card-type electronic money, small electronic devices such as smart watches, etc.), home and small industrial applications (e.g., electric tools, golf carts, home/nursing/industrial robots), large industrial applications (e.g. forklifts, elevators, harbor cranes), transportation systems (e.g. hybrid vehicles, electric vehicles, buses, trains, electrically assisted bicycles, Electric motorcycles, etc.), power system applications (for example, various power generation, road conditioners, smart grids, general household installation type storage systems, etc.), medical applications (medical equipment such as earphone hearing aids), medical applications (dosing management systems, etc.), the IoT field, and space/deep-sea applications (for example, the fields of space probes, submersible research vessels, etc.).

Claims (14)

  1. 電極活物質、導電助剤および電解液を含む半固体電極層と、
    集電体とを有する半固体電極を含み、
    　前記半固体電極は、前記半固体電極層と前記集電体との間にカーボン層を有する二次電池。     a semi-solid electrode layer containing an electrode active material, a conductive aid and an electrolytic solution;
    a semi-solid electrode having a current collector;
    A secondary battery in which the semi-solid electrode has a carbon layer between the semi-solid electrode layer and the current collector.
  2. 前記カーボン層はカーボンブラックを含み、
    前記カーボンブラックの含有量は、前記カーボン層全量に対して、２０体積％以上６０体積％以下である、請求項１に記載の二次電池。     The carbon layer contains carbon black,
    The secondary battery according to claim 1, wherein the content of said carbon black is 20% by volume or more and 60% by volume or less with respect to the total amount of said carbon layer.
  3. 前記カーボン層はカーボンブラックが分散されたポリマー層である、請求項１または２に記載の二次電池。 3. The secondary battery according to claim 1, wherein said carbon layer is a polymer layer in which carbon black is dispersed.
  4. 前記半固体電極層の導電率が１．０×１０－２Ｓ／ｃｍ未満である、請求項１～３のいずれかに記載の二次電池。 4. The secondary battery according to claim 1, wherein said semi-solid electrode layer has a conductivity of less than 1.0×10 −2 S/cm.
  5. 前記二次電池は半固体正極および半固体負極を含み、前記半固体正極および前記半固体負極の少なくとも一方が前記半固体電極に相当する、請求項１～４のいずれかに記載の二次電池。 5. The secondary battery according to claim 1, wherein said secondary battery includes a semi-solid positive electrode and a semi-solid negative electrode, and at least one of said semi-solid positive electrode and said semi-solid negative electrode corresponds to said semi-solid electrode. .
  6. 前記半固体電極層における前記電極活物質の含有量は、前記半固体電極層全量に対して、５０質量％以上９０質量％以下である、請求項１～５のいずれかに記載の二次電池。 The secondary battery according to any one of claims 1 to 5, wherein the content of the electrode active material in the semi-solid electrode layer is 50% by mass or more and 90% by mass or less with respect to the total amount of the semi-solid electrode layer. .
  7. 前記半固体電極層における前記導電助剤の含有量は、前記半固体電極層全量に対して、０．１質量％以上１０質量％以下である、請求項１～６のいずれかに記載の二次電池。 The content of the conductive agent in the semi-solid electrode layer is 0.1% by mass or more and 10% by mass or less with respect to the total amount of the semi-solid electrode layer, The two according to any one of claims 1 to 6. next battery.
  8. 前記半固体電極層における前記電解液の含有量は、前記半固体電極層全量に対して、３０体積％以上７０体積％以下である、請求項１～７のいずれかに記載の二次電池。 8. The secondary battery according to claim 1, wherein the content of said electrolyte in said semi-solid electrode layer is 30% by volume or more and 70% by volume or less with respect to the total amount of said semi-solid electrode layer.
  9. 前記二次電池は半固体正極および半固体負極を含み、前記半固体電極が前記半固体正極に相当する、請求項１～８のいずれかに記載の二次電池。 The secondary battery according to any one of claims 1 to 8, wherein said secondary battery comprises a semi-solid positive electrode and a semi-solid negative electrode, and said semi-solid electrode corresponds to said semi-solid positive electrode.
  10. 前記半固体正極が有する半固体正極層における導電助剤の含有量は、前記半固体正極層全量に対して、０．５質量％以上２質量％以下である、請求項９に記載の二次電池。 The secondary according to claim 9, wherein the content of the conductive aid in the semi-solid positive electrode layer of the semi-solid positive electrode is 0.5% by mass or more and 2% by mass or less with respect to the total amount of the semi-solid positive electrode layer. battery.
  11. 前記カーボン層の厚みが０．１μｍ以上１０μｍ以下である、請求項１～１０のいずれかに記載の二次電池。 The secondary battery according to any one of claims 1 to 10, wherein the carbon layer has a thickness of 0.1 µm or more and 10 µm or less.
  12. 前記半固体電極の面積当りの容量が４ｍＡｈ／ｃｍ２以上である、請求項１～１１のいずれかに記載の二次電池。 The secondary battery according to any one of claims 1 to 11, wherein the semi-solid electrode has a capacity per area of 4 mAh/cm 2 or more.
  13. 前記半固体電極層はリチウムイオンを吸蔵放出可能な電極層である、請求項１～１２のいずれかに記載の二次電池。 13. The secondary battery according to claim 1, wherein said semi-solid electrode layer is an electrode layer capable of intercalating and deintercalating lithium ions.
  14. 請求項１～１３のいずれかに記載の二次電池を製造する方法であって、以下の工程を含む、二次電池の製造方法：
    　電極活物質、導電助剤および電解液を混合して、電極層用スラリーを調合する調合工程；
    　集電体にカーボン層を形成するカーボン層形成工程；
    　カーボン層を有する集電体に電極層用スラリーを塗布し、電極を形成する塗布工程；
    　前記電極と電極の間にセパレータが配置されるように、積層し積層体を作製する積層工程；および
    　前記積層体を外装体に封入する封入工程。     A method for manufacturing the secondary battery according to any one of claims 1 to 13, comprising the following steps:
    A preparation step of mixing an electrode active material, a conductive aid and an electrolytic solution to prepare an electrode layer slurry;
    Carbon layer forming step of forming a carbon layer on the current collector;
    A coating step of coating an electrode layer slurry on a current collector having a carbon layer to form an electrode;
    a stacking step of stacking and forming a stack such that a separator is disposed between the electrodes; and an encapsulation step of sealing the stack in an outer package.
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Citations (5)

* Cited by examiner, † Cited by third party
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JP2001351612A (en) * 2000-06-06 2001-12-21 Matsushita Battery Industrial Co Ltd Non-aqueous electrolyte secondary battery
JP2008541398A (en) * 2005-05-17 2008-11-20 ザ ジレット カンパニー Wafer alkaline battery
JP2013535801A (en) * 2010-08-18 2013-09-12 マサチューセッツ インスティテュート オブ テクノロジー Static fluid redox electrode
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WO2016158480A1 (en) * 2015-03-30 2016-10-06 東洋インキＳｃホールディングス株式会社 Electrically conductive composition, under layer-attached current collector for electric storage devices, electrode for electric storage devices, and electric storage device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001351612A (en) * 2000-06-06 2001-12-21 Matsushita Battery Industrial Co Ltd Non-aqueous electrolyte secondary battery
JP2008541398A (en) * 2005-05-17 2008-11-20 ザ ジレット カンパニー Wafer alkaline battery
JP2013535801A (en) * 2010-08-18 2013-09-12 マサチューセッツ インスティテュート オブ テクノロジー Static fluid redox electrode
JP2016500465A (en) * 2012-12-13 2016-01-12 ２４エム・テクノロジーズ・インコーポレイテッド２４Ｍ Ｔｅｃｈｎｏｌｏｇｉｅｓ， Ｉｎｃ． Semi-solid electrode with high speed capability
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