WO2023058557A1 - Batterie secondaire et son procédé de production - Google Patents

Batterie secondaire et son procédé de production 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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semi
solid
electrode layer
secondary battery
electrode
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PCT/JP2022/036505
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English (en)
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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    • 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.

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Abstract

La présente invention concerne une batterie secondaire dans laquelle la résistance interfaciale entre une couche d'électrode et un collecteur de courant est encore réduite et des caractéristiques de taux sensiblement supérieures sont obtenues. La présente invention concerne une batterie secondaire 10 comprenant une électrode semi-solide 1 qui possède : une couche d'électrode semi-solide 7 comprenant un matériau actif d'électrode 2, un agent auxiliaire conducteur 3, et une solution d'électrolyte 4 ; et un collecteur de courant 5. L'électrode semi-solide 1 comprend une couche de carbone 6 entre la couche d'électrode semi-solide 7 et le collecteur de courant 5.
PCT/JP2022/036505 2021-10-06 2022-09-29 Batterie secondaire et son procédé de production WO2023058557A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001351612A (ja) * 2000-06-06 2001-12-21 Matsushita Battery Industrial Co Ltd 非水電解液二次電池
JP2008541398A (ja) * 2005-05-17 2008-11-20 ザ ジレット カンパニー ウェーハアルカリ電池
JP2013535801A (ja) * 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 静止型流体レドックス電極
JP2016500465A (ja) * 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． 高速度能力を有する半固体電極
WO2016158480A1 (fr) * 2015-03-30 2016-10-06 東洋インキＳｃホールディングス株式会社 Composition électriquement conductrice, collecteur de courant pour dispositifs de stockage d'électricité fixé à une sous-couche, électrode pour dispositifs de stockage d'électricité, et dispositif de stockage d'électricité

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001351612A (ja) * 2000-06-06 2001-12-21 Matsushita Battery Industrial Co Ltd 非水電解液二次電池
JP2008541398A (ja) * 2005-05-17 2008-11-20 ザ ジレット カンパニー ウェーハアルカリ電池
JP2013535801A (ja) * 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 静止型流体レドックス電極
JP2016500465A (ja) * 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． 高速度能力を有する半固体電極
WO2016158480A1 (fr) * 2015-03-30 2016-10-06 東洋インキＳｃホールディングス株式会社 Composition électriquement conductrice, collecteur de courant pour dispositifs de stockage d'électricité fixé à une sous-couche, électrode pour dispositifs de stockage d'électricité, et dispositif de stockage d'électricité

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