WO2023187466A1 - 正極材料およびこれを用いた二次電池 - Google Patents

正極材料およびこれを用いた二次電池 Download PDF

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WO2023187466A1
WO2023187466A1 PCT/IB2023/000145 IB2023000145W WO2023187466A1 WO 2023187466 A1 WO2023187466 A1 WO 2023187466A1 IB 2023000145 W IB2023000145 W IB 2023000145W WO 2023187466 A1 WO2023187466 A1 WO 2023187466A1
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Prior art keywords
positive electrode
porous carbon
electrode active
active material
pores
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PCT/IB2023/000145
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English (en)
French (fr)
Japanese (ja)
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WO2023187466A8 (ja
Inventor
珍光 李
航 荻原
一生 大谷
美咲 藤本
大介 伊藤
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Renault SAS
Nissan Motor Co Ltd
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Renault SAS
Nissan Motor Co Ltd
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Priority to US18/849,941 priority Critical patent/US20250210631A1/en
Priority to JP2024510541A priority patent/JPWO2023187466A1/ja
Priority to CN202380030846.7A priority patent/CN118946984A/zh
Priority to EP23778570.4A priority patent/EP4503183A4/en
Publication of WO2023187466A1 publication Critical patent/WO2023187466A1/ja
Publication of WO2023187466A8 publication Critical patent/WO2023187466A8/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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

Definitions

  • the present invention relates to a positive electrode material and a secondary battery using the same.
  • lithium secondary batteries that are currently in widespread use use a flammable organic electrolyte as the electrolyte.
  • Such liquid-based lithium secondary batteries require more stringent safety measures against leakage, short circuits, overcharging, etc. than other batteries.
  • a solid electrolyte is a material mainly composed of an ion conductor capable of ion conduction in a solid state. Therefore, in principle, all-solid-state lithium secondary batteries do not suffer from various problems caused by flammable organic electrolytes, unlike conventional liquid-based lithium secondary batteries. Furthermore, in general, the use of high-potential, large-capacity positive electrode materials and large-capacity negative electrode materials can significantly improve the output density and energy density of the battery. For example, elemental sulfur (S 8 ) has an extremely large theoretical capacity of about 1670 mAh/g, and has the advantages of being low cost and abundant in resources.
  • Japanese Patent Application Laid-Open No. 2010-95390 discloses that a mesoporous carbon composite material containing at least mesoporous carbon and sulfur disposed in the mesopores of the mesoporous carbon is used in an all-solid-state battery. A technology for use as a positive electrode material has been proposed. According to Japanese Unexamined Patent Publication No. 2010-95390, by using a positive electrode material having such a configuration, electron conductivity can be improved by making sulfur into fine particles and compounding with mesoporous carbon, and battery characteristics can be improved.
  • an object of the present invention is to provide a means for further reducing the internal resistance of a secondary battery using a positive electrode active material containing sulfur.
  • the present inventors conducted extensive studies to solve the above problems. As a result, the inventors found that the above problems could be solved by using a positive electrode material containing lithium halide together with a positive electrode active material containing sulfur in the pores of a porous carbon material, and the present invention was completed. .
  • One form of the present invention includes a porous carbon material, a positive electrode active material containing sulfur, and lithium halide, and at least a part of the positive electrode active material and at least a part of the lithium halide are A positive electrode material characterized in that it is disposed within the pores of a porous carbon material.
  • FIG. 1 is a perspective view showing the appearance of a flat stacked all-solid-state lithium secondary battery, which is an embodiment of the present invention.
  • FIG. 2 is a sectional view taken along line 2-2 shown in FIG.
  • FIG. 3(a) is a schematic cross-sectional view of a conventional positive electrode material
  • FIG. 3(b) is a schematic cross-sectional view of a positive electrode material according to an embodiment of the present invention.
  • FIG. 4 is an XRD spectrum of the positive electrode material produced in Example 1.
  • FIG. 5 is an XRD spectrum of the positive electrode material produced in Example 6.
  • FIG. 6 is an XRD spectrum of the positive electrode material produced in Comparative Example 1.
  • FIG. 7 is an XRD spectrum of the positive electrode material produced in Comparative Example 2.
  • the present invention will be described using as an example a stacked type (internal parallel connection type) all-solid-state lithium secondary battery, which is one form of a secondary battery.
  • the solid electrolyte constituting the all-solid-state lithium secondary battery is a material mainly composed of an ion conductor capable of ion conduction in a solid state.
  • all-solid-state lithium secondary batteries have the advantage that, unlike conventional liquid-based lithium secondary batteries, various problems caused by flammable organic electrolytes do not occur in principle.
  • the use of high-potential, large-capacity positive electrode materials and large-capacity negative electrode materials has the advantage that the output density and energy density of the battery can be significantly improved.
  • One form of the present invention includes a porous carbon material, a positive electrode active material containing sulfur, and lithium halide, and at least a part of the positive electrode active material and at least a part of the lithium halide are A positive electrode material characterized in that it is disposed within the pores of a porous carbon material. According to the positive electrode material according to this embodiment, the internal resistance of the secondary battery can be further reduced.
  • the internal resistance of the secondary battery can be further reduced.
  • FIG. 1 is a perspective view showing the appearance of a flat stacked all-solid-state lithium secondary battery that is an embodiment of the present invention.
  • FIG. 2 is a sectional view taken along line 2-2 shown in FIG.
  • a flat stacked non-bipolar lithium secondary battery shown in FIGS. 1 and 2 will be described in detail as an example.
  • the internal electrical connection form (electrode structure) of the lithium secondary battery when looking at the internal electrical connection form (electrode structure) of the lithium secondary battery according to this embodiment, whether it is a non-bipolar type (internal parallel connection type) battery or a bipolar type (internal series connection type) battery. can also be applied.
  • the stacked battery 10a has a rectangular flat shape, and a negative electrode current collector plate 25 and a positive electrode current collector plate 27 for extracting power are pulled out from both sides of the stacked battery 10a.
  • the power generation element 21 is surrounded by the battery exterior material (laminate film 29) of the stacked battery 10a, and the periphery thereof is heat-sealed, and the power generation element 21 has the negative electrode current collector plate 25 and the positive electrode current collector plate 27 connected to the outside. It is sealed when pulled out.
  • the lithium secondary battery according to this embodiment is not limited to a stacked and flat-shaped battery.
  • a wound type lithium secondary battery may have a cylindrical shape, or may be a cylindrical battery that has been deformed into a rectangular flat shape. , but is not particularly limited.
  • the above-mentioned cylindrical shape is not particularly limited, and a laminate film or a conventional cylindrical can (metal can) may be used for the exterior material.
  • the power generation element is housed inside a laminate film containing aluminum. With this form, weight reduction can be achieved.
  • the terminals may be formed using, for example, a cylindrical can (metal can) instead of a tab.
  • the stacked battery 10a of the present embodiment has a structure in which a flat, substantially rectangular power generation element 21 in which charge and discharge reactions actually proceed is sealed inside a laminate film 29 that is a battery exterior material.
  • the power generation element 21 has a structure in which a positive electrode, a solid electrolyte layer 17, and a negative electrode are laminated.
  • the positive electrode has a structure in which positive electrode active material layers 15 containing a positive electrode active material are disposed on both sides of a positive electrode current collector 11''.
  • the negative electrode has a structure in which positive electrode active material layers 15 containing a positive electrode active material are arranged on both sides of a negative electrode current collector 11'.
  • active material layers 13 It has a structure in which active material layers 13 are arranged.Specifically, one positive electrode active material layer 15 and an adjacent negative electrode active material layer 13 face each other with a solid electrolyte layer 17 in between, A positive electrode, a solid electrolyte layer, and a negative electrode are stacked in this order.Thereby, the adjacent positive electrode, solid electrolyte layer, and negative electrode constitute one single cell layer 19.Therefore, the stacked battery 10a shown in FIG. , it can be said that it has a configuration in which a plurality of cell layers 19 are stacked and electrically connected in parallel.
  • the negative electrode active material layer 13 is disposed on only one side of the outermost layer negative electrode current collectors located at both outermost layers of the power generation element 21, but active material layers are disposed on both surfaces. It's okay to be hit. That is, instead of using a current collector exclusively for the outermost layer with an active material layer provided on only one side, a current collector with active material layers on both sides may be used as it is as the outermost layer current collector. Further, in some cases, the negative electrode active material layer 13 and the positive electrode active material layer 15 may be used as the negative electrode and the positive electrode, respectively, without using the current collectors (11', 11'').
  • a negative current collector plate (tab) 25 and a positive current collector plate (tab) 27 that are electrically connected to each electrode (positive electrode and negative electrode) are attached to the negative electrode current collector 11' and the positive electrode current collector 11'', respectively. It has a structure in which it is sandwiched between the ends of the laminate film 29, which is an exterior material, and led out to the outside of the laminate film 29.
  • the positive electrode current collector plate 27 and the negative electrode current collector plate 25 each have a structure in which they are sandwiched between the ends of the laminate film 29, which is an exterior material. It may be attached to the positive electrode current collector 11'' and negative electrode current collector 11' of each electrode via a positive electrode lead and a negative electrode lead (not shown) by ultrasonic welding, resistance welding, or the like.
  • the current collector has a function of mediating the movement of electrons from the electrode active material layer (positive electrode active material layer or negative electrode active material layer). There is no particular restriction on the material constituting the current collector.
  • the constituent material of the current collector for example, metal or conductive resin may be used.
  • metals include aluminum, nickel, iron, stainless steel, titanium, copper, and the like.
  • a cladding material of nickel and aluminum, a cladding material of copper and aluminum, etc. may be used.
  • it may be a foil whose metal surface is coated with aluminum.
  • aluminum, stainless steel, copper, and nickel are preferred from the viewpoints of electron conductivity, battery operating potential, adhesion of the negative electrode active material to the current collector by sputtering, and the like.
  • examples of the resin having conductivity include resins in which a conductive filler is added to a non-conductive polymer material.
  • the current collector may have a single-layer structure made of a single material, or may have a laminated structure in which layers made of these materials are appropriately combined. From the viewpoint of reducing the weight of the current collector, it is preferable to include at least a conductive resin layer made of a resin having conductivity. Further, from the viewpoint of blocking the movement of lithium ions between the cell layers, a metal layer may be provided on a part of the current collector. Furthermore, if the negative electrode active material layer and the positive electrode active material layer, which will be described later, have conductivity by themselves and can exhibit a current collection function, it is possible to use a current collector as a member separate from these electrode active material layers. It is not necessary. In such a form, the negative electrode active material layer described later directly constitutes the negative electrode, and the positive electrode active material layer described later directly constitutes the positive electrode.
  • the negative electrode active material layer 13 includes a negative electrode active material.
  • the type of negative electrode active material is not particularly limited, but includes carbon materials, metal oxides, and metal active materials.
  • carbon materials include natural graphite, artificial graphite, mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon.
  • metal oxides include Nb 2 O 5 and Li 4 Ti 5 O 12 .
  • a metal active material such as a silicon-based negative electrode active material or a tin-based negative electrode active material may be used.
  • silicon and tin belong to Group 14 elements, and are known to be negative electrode active materials that can greatly improve the capacity of nonaqueous electrolyte secondary batteries. Since these simple substances can absorb and release a large number of charge carriers (lithium ions, etc.) per unit volume (mass), they become high-capacity negative electrode active materials.
  • a silicon oxide such as SiOx (0.3 ⁇ x ⁇ 1.6) that is disproportionated into two phases, a Si phase and a silicon oxide phase.
  • the range of x is more preferably 0.5 ⁇ x ⁇ 1.5, and even more preferably 0.7 ⁇ x ⁇ 1.2.
  • an alloy containing silicon (silicon-containing alloy negative electrode active material) may be used.
  • negative electrode active materials containing the tin element include Sn alone, tin alloys (Cu-Sn alloys, Co-Sn alloys), amorphous tin oxides, tin silicon oxides, and the like.
  • SnB 0.4 P 0.6 O 3.1 is exemplified as the amorphous tin oxide.
  • SnSiO 3 is exemplified as the tin silicon oxide.
  • a metal containing lithium may be used as the negative electrode active material.
  • Such a negative electrode active material is not particularly limited as long as it is an active material containing lithium, and examples thereof include metal lithium and lithium-containing alloys.
  • lithium-containing alloys include alloys of Li and at least one of In, Al, Si, and Sn.
  • two or more types of negative electrode active materials may be used together.
  • negative electrode active materials other than those mentioned above may be used.
  • the negative electrode active material preferably contains metallic lithium, a silicon-based negative electrode active material, or a tin-based negative electrode active material, and particularly preferably contains metallic lithium.
  • the content of the negative electrode active material in the negative electrode active material layer is not particularly limited, but for example, it is preferably within the range of 40 to 99% by mass, and preferably within the range of 50 to 90% by mass. More preferred.
  • the negative electrode active material layer further includes a solid electrolyte.
  • the solid electrolyte By including the solid electrolyte in the negative electrode active material layer, the ionic conductivity of the negative electrode active material layer can be improved.
  • the solid electrolyte include sulfide solid electrolytes and oxide solid electrolytes, and sulfide solid electrolytes are preferred.
  • the solid electrolyte refers to a material mainly composed of an ion conductor capable of ion conduction in a solid state, and in particular, the lithium ion conductivity at room temperature (25°C) is 1 ⁇ 10 ⁇ 5 S/ Refers to materials with a diameter of cm or more.
  • the value of ionic conductivity can be measured by an AC impedance method.
  • Examples of the sulfide solid electrolyte include LiI - Li2S - SiS2 , LiI- Li2SP2O5 , LiI- Li3PO4 - P2S5 , Li2S - P2S5 , LiI - Li3PS4 , LiI-LiBr- Li3PS4 , Li3PS4 , Li2S - P2S5- LiI, Li2S - P2S5 - Li2O , Li2S -P 2S5 - Li2O -LiI, Li2S - SiS2, Li2S- SiS2 -LiI, Li2S - SiS2 - LiBr , Li2S - SiS2 -LiCl, Li2S - SiS2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 S-B 2 S 3 , Li 2 S-P 2 S 5
  • the sulfide solid electrolyte may have, for example, a Li 3 PS 4 skeleton, a Li 4 P 2 S 7 skeleton, or a Li 4 P 2 S 6 skeleton.
  • Examples of the sulfide solid electrolyte having a Li3PS4 skeleton include LiI- Li3PS4 , LiI-LiBr- Li3PS4 , and Li3PS4 .
  • examples of the sulfide solid electrolyte having a Li 4 P 2 S 7 skeleton include a Li-P-S solid electrolyte (for example, Li 7 P 3 S 11 ) called LPS.
  • the sulfide solid electrolyte for example, LGPS represented by Li (4-x) Ge (1-x) P x S 4 (x satisfies 0 ⁇ x ⁇ 1) or the like may be used.
  • a sulfide solid electrolyte containing the P element is preferable, and a material containing Li 2 SP 2 S 5 as a main component is more preferable.
  • the sulfide solid electrolyte may contain halogen (F, Cl, Br, I).
  • the sulfide solid electrolyte comprises Li 6 PS 5 X, where X is Cl, Br or I, preferably Cl.
  • the sulfide solid electrolyte may be sulfide glass, crystallized sulfide glass, or a crystalline material obtained by a solid phase method.
  • sulfide glass can be obtained, for example, by performing mechanical milling (ball mill, etc.) on a raw material composition.
  • crystallized sulfide glass can be obtained, for example, by heat-treating sulfide glass at a temperature equal to or higher than the crystallization temperature.
  • the ionic conductivity (for example, Li ion conductivity) of the sulfide solid electrolyte at room temperature (25° C.) is preferably, for example, 1 ⁇ 10 ⁇ 5 S/cm or more, and 1 ⁇ 10 ⁇ 4 S/cm or more. More preferably, it is at least cm.
  • oxide solid electrolyte examples include compounds having a NASICON type structure.
  • compounds having a NASICON type structure include a compound (LAGP) represented by the general formula Li 1+x Al x Ge 2-x (PO 4 ) 3 (0 ⁇ x ⁇ 2), and a compound represented by the general formula Li 1+x Al x Ti 2 -x (PO 4 ) 3 (0 ⁇ x ⁇ 2) (LATP) and the like can be mentioned.
  • LAGP a compound represented by the general formula Li 1+x Al x Ge 2-x (PO 4 ) 3 (0 ⁇ x ⁇ 2)
  • Li 1+x Al x Ti 2 -x (PO 4 ) 3 (0 ⁇ x ⁇ 2)
  • LATP lithium x Al x Ti 2 -x
  • other examples of oxide solid electrolytes include LiLaTiO (e.g., Li 0.34 La 0.51 TiO 3 ), LiPON (e.g., Li 2.9 PO 3.3 N 0.46 ), LiLaZrO (e.g. , Li 7 La 3 Zr 2
  • the content of the solid electrolyte in the negative electrode active material layer is, for example, preferably in the range of 1 to 60% by mass, more preferably in the range of 10 to 50% by mass.
  • the negative electrode active material layer may further contain at least one of a conductive additive and a binder.
  • conductive aids include metals such as aluminum, stainless steel (SUS), silver, gold, copper, and titanium; alloys or metal oxides containing these metals; carbon fibers (specifically, vapor-grown carbon fibers); (VGCF), polyacrylonitrile carbon fiber, pitch carbon fiber, rayon carbon fiber, activated carbon fiber, etc.), carbon nanotubes (CNT), carbon black (specifically, acetylene black, Ketjen black (registered trademark)) , furnace black, channel black, thermal lamp black, etc.), but are not limited to these. Further, a particulate ceramic material or resin material coated with the above metal material by plating or the like can also be used as a conductive aid.
  • conductive additives from the viewpoint of electrical stability, it is preferable to include at least one selected from the group consisting of aluminum, stainless steel, silver, gold, copper, titanium, and carbon; , silver, gold, and carbon, and more preferably at least one type of carbon.
  • These conductive aids may be used alone or in combination of two or more.
  • the content of the conductive additive in the negative electrode active material layer is not particularly limited, but is preferably 0 to 10% by mass based on the total mass of the negative electrode active material layer. , more preferably 2 to 8% by mass, and even more preferably 4 to 7% by mass. Within this range, it becomes possible to form a stronger electron conduction path in the negative electrode active material layer, and it is possible to effectively contribute to improving battery characteristics.
  • the binder is not particularly limited, but examples include the following materials: polybutylene terephthalate, polyethylene terephthalate, polyvinylidene fluoride (PVDF) (including compounds in which hydrogen atoms are replaced with other halogen elements) , polyethylene, polypropylene, polymethylpentene, polybutene, polyethernitrile, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene-butadiene rubber (SBR), ethylene-propylene ⁇ Thermoplastic polymers such as diene copolymers, styrene/butadiene/styrene block copolymers and their hydrogenated products, styrene/isoprene/styrene block copolymers and their hydrogenated products, tetrafluoroethylene/hexafluoropropylene
  • PVDF
  • FEP Polymer
  • PFA tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer
  • EFE ethylene/tetrafluoroethylene copolymer
  • PCTFE polychlorotrifluoroethylene
  • ECTFE ethylene/chlorotrifluoroethylene copolymer
  • fluororesins such as polyvinyl fluoride (PVF), vinylidene fluoride-hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber ( VDF-HFP-TFE-based fluororubber), vinylidene fluoride-pentafluoropropylene-based fluororubber (VDF-PFP-based fluorubber), vinylidene fluoride-pentafluoropropylene-based fluororubber (VDF
  • Examples include vinylidene fluoride-based fluororubbers and epoxy resins.
  • polyimide, styrene-butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferred.
  • the thickness of the negative electrode active material layer varies depending on the configuration of the intended secondary battery, but is preferably within the range of 0.1 to 1000 ⁇ m, for example.
  • the solid electrolyte layer is a layer that is interposed between the above-described positive electrode active material layer and negative electrode active material layer and essentially contains a solid electrolyte.
  • solid electrolyte contained in the solid electrolyte layer
  • solid electrolytes and preferred forms thereof exemplified in the section of the negative electrode active material layer may be similarly employed.
  • solid electrolytes other than the solid electrolytes described above may be used in combination.
  • the solid electrolyte layer may further contain a binder in addition to the above-described predetermined solid electrolyte.
  • a binder in addition to the above-described predetermined solid electrolyte.
  • the binder that can be contained in the solid electrolyte layer the examples and preferred forms described in the section of the negative electrode active material layer can be similarly adopted.
  • the thickness of the solid electrolyte layer varies depending on the configuration of the intended lithium secondary battery, but from the viewpoint of improving the volumetric energy density of the battery, it is preferably 800 ⁇ m or less, more preferably 700 ⁇ m or less, More preferably, it is 600 ⁇ m or less. On the other hand, there is no particular restriction on the lower limit of the thickness of the solid electrolyte layer, but it is preferably 1 ⁇ m or more, more preferably 5 ⁇ m or more, and even more preferably 10 ⁇ m or more.
  • the positive electrode active material layer includes a positive electrode material according to one embodiment of the present invention.
  • the positive electrode material includes a porous carbon material, a positive electrode active material containing sulfur, and lithium halide. At least a portion of the positive electrode active material and at least a portion of the lithium halide are arranged within the pores of the porous carbon material.
  • the type of positive electrode active material containing sulfur is not particularly limited, but in addition to elemental sulfur (S), particles or thin films of organic sulfur compounds or inorganic sulfur compounds may be used. Any material may be used as long as it can release lithium ions during discharge and occlude lithium ions during discharge.
  • the organic sulfur compound include disulfide compounds, sulfur-modified polyacrylonitrile typified by the compound described in International Publication No. 2010/044437, sulfur-modified polyisoprene, rubeanic acid (dithiooxamide), polysulfide carbon, and the like.
  • disulfide compounds sulfur-modified polyacrylonitrile, and rubeanic acid are preferred, and sulfur-modified polyacrylonitrile is particularly preferred.
  • the disulfide compound those having a dithiobiurea derivative, a thiourea group, a thioisocyanate, or a thioamide group are more preferable.
  • the sulfur-modified polyacrylonitrile is a modified polyacrylonitrile containing sulfur atoms, which is obtained by mixing sulfur powder and polyacrylonitrile and heating the mixture under an inert gas or reduced pressure.
  • the estimated structure can be found, for example, in Chem. Mater.
  • polyacrylonitrile is ring-closed to become polycyclic, and at least a part of S is bonded to C.
  • the compound described in this document has strong peak signals near 1330 cm -1 and 1560 cm -1 in the Raman spectrum, and peaks near 307 cm -1 , 379 cm -1 , 472 cm -1 , and 929 cm -1 do.
  • inorganic sulfur compounds are preferable because of their excellent stability, and specifically include elemental sulfur (S), S-carbon composite, TiS 2 , TiS 3 , TiS 4 , NiS, NiS 2 , CuS, FeS 2 , Li Examples include 2S , MoS2 , MoS3 , MnS, MnS2 , CoS, CoS2, and the like.
  • elemental sulfur (S), TiS 2 , TiS 3 , TiS 4 , FeS 2 and MoS 2 are preferred, elemental sulfur (S), TiS 2 and FeS 2 are more preferred, and from the viewpoint of high capacity, Sulfur (S) is particularly preferred.
  • S elemental sulfur
  • ⁇ sulfur, ⁇ sulfur, or ⁇ sulfur having an S 8 structure can be used.
  • the positive electrode material according to this embodiment may further include a positive electrode active material (other positive electrode active material) that does not contain sulfur.
  • positive electrode active materials include, for example, layered rock salt active materials such as LiCoO 2 , LiMnO 2 , LiNiO 2 , LiVO 2 , Li(Ni-Mn-Co)O 2 , LiMn 2 O 4 , LiNi 0.5 Mn
  • spinel-type active materials such as 1.5 O 4
  • olivine-type active materials such as LiFePO 4 and LiMnPO 4
  • Si-containing active materials such as Li 2 FeSiO 4 and Li 2 MnSiO 4 .
  • oxide active materials other than those mentioned above include Li 4 Ti 5 O 12 .
  • the content ratio of the positive electrode active material containing sulfur to the total amount of 100% by mass of the positive electrode active material is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass.
  • the content is more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.
  • the positive electrode material according to this embodiment includes lithium halide (LiX, where X is a halogen atom).
  • lithium halides include lithium fluoride, lithium chloride, lithium bromide, and lithium iodide.
  • lithium chloride or lithium iodide is preferable, and lithium iodide is more preferable because of its excellent ionic conductivity. Two or more types of lithium halides may be used in combination.
  • the positive electrode material according to this embodiment essentially includes a carbon material having pores (porous carbon material).
  • the specific form of the porous carbon material included in the positive electrode material according to this embodiment is not particularly limited as long as it is a carbon material having pores, and conventionally known materials may be appropriately employed.
  • Porous carbon materials include, for example, activated carbon, Ketjenblack (registered trademark) (highly conductive carbon black), (oil) carbon black such as furnace black, channel black, acetylene black, thermal black, lamp black, coke, Examples include carbon particles (carbon carrier) made of natural graphite, artificial graphite, and the like.
  • a carbon material with a porous structure in which the shape of the mold is transferred is synthesized by mixing a mold such as ceramics with a carbon raw material such as resin, firing it in an inert atmosphere, and then melting the mold with acid. However, this may be used as a carbon material. At this time, the pore diameter and pore volume of the resulting porous carbon material can be changed by appropriately adjusting the particle size of the template and the blending ratio of the carbon raw materials.
  • the main component of the porous carbon material is preferably carbon.
  • the main component is carbon refers to containing carbon atoms as the main component, and is a concept that includes both “consisting only of carbon atoms” and “consisting substantially of carbon atoms.” "Substantially consisting of carbon atoms” means that the inclusion of impurities of about 2 to 3% by mass or less can be tolerated.
  • the BET specific surface area of the porous carbon material is not particularly limited, but is preferably 200 m 2 /g or more, more preferably 500 m 2 /g or more, even more preferably 800 m 2 /g or more, It is especially preferable that it is 1200 m 2 /g or more, and it is most preferable that it is 1500 m 2 /g or more. Further, the total pore volume of the porous carbon material is preferably 1.0 mL/g or more, more preferably 1.3 mL/g or more, and even more preferably 1.5 mL/g or more. .
  • the values of the BET specific surface area and total pore volume of the porous carbon material can be measured by nitrogen adsorption/desorption measurement. This nitrogen adsorption/desorption measurement is performed using BELSORP mini manufactured by Microtrac Bell Co., Ltd., at a temperature of -196°C by a multi-point method. The BET specific surface area is determined from the adsorption isotherm in the relative pressure range of 0.01 ⁇ P/P 0 ⁇ 0.05. Further, the total pore volume is determined from the volume of adsorbed N 2 at a relative pressure of 0.96.
  • the average pore diameter of the porous carbon material is not particularly limited, but is preferably 100 nm or less, more preferably 50 nm or less, and particularly preferably 30 nm or less. If the average pore diameter of the porous carbon material is within these ranges, the reaction area can be increased by increasing the contact area with the positive electrode active material or lithium halide. In addition, electrons can be sufficiently supplied to active materials located away from the pore walls among the sulfur-containing positive electrode active materials disposed inside the pores. As a result, the effects of the present invention can be more significantly obtained.
  • the value of the average pore diameter of the porous carbon material can be calculated by nitrogen adsorption/desorption measurement in the same way as when determining the BET specific surface area and total pore volume. In this specification, the pore distribution of the porous carbon material is obtained using the BJH method. Note that the lower limit of the average pore diameter of the porous carbon material is also not particularly limited, and is, for example, 1 nm or more.
  • the porous carbon material preferably has pores with a pore diameter in the range of 1 to 100 nm. Further, among the pores possessed by the porous carbon material, the percentage of the pore volume of pores with a pore diameter in the range of 1 to 4 nm to the pore volume of pores in the pore diameter range of 1 to 100 nm is 20% or less. It is preferable that Thereby, the positive electrode active material and/or lithium halide can be easily retained inside the pores. Further, even inside the pores, on the surface of the positive electrode active material, not only electrons can smoothly enter and exit through the porous carbon material, but also charge carriers can smoothly enter and exit through the lithium halide.
  • the value of the above percentage is more preferably 18% or less, still more preferably 15% or less, and even more preferably 12% or less. , particularly preferably 9% or less.
  • the lower limit of the above percentage is not particularly limited, but is, for example, 3% or more.
  • the average particle diameter (primary particle diameter) of the porous carbon material is not particularly limited, but is preferably 0.05 to 50 ⁇ m, more preferably 0.1 to 20 ⁇ m, and 0.5 ⁇ m. More preferably, the thickness is ⁇ 10 ⁇ m.
  • the particle diameter of a porous carbon material means the maximum distance L among the distances between any two points on the outline of a particle of a porous carbon material.
  • the value of "average particle diameter of porous carbon material” is determined by the number of particles observed in several to several tens of fields of view using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The value calculated as the arithmetic mean value of the diameter shall be adopted.
  • the positive electrode material according to this embodiment includes a porous carbon material, a positive electrode active material containing sulfur, and a lithium halide, and includes at least a portion of the positive electrode active material and at least a portion of the halogen.
  • lithium chloride is disposed within the pores of the porous carbon material.
  • FIG. 3(a) is a schematic cross-sectional view of a conventional positive electrode material 100'. Further, FIG. 3(b) is a schematic cross-sectional view of the positive electrode material 100 according to one embodiment of the present invention.
  • the porous carbon material 110 has a large number of pores 110a, and the pores 110a are filled with a positive electrode active material 120 containing sulfur.
  • the reaction resistance of the electrode reaction is high. This is because, in addition to the fact that the positive electrode active material 120 containing sulfur has low conductivity, the positive electrode active material 120 generates Li 2 S with low ionic conductivity near the interface 140 with the solid electrolyte 130 during the electrode reaction. This is thought to be because the resistance to diffusion of lithium ions within the positive electrode material becomes high.
  • the positive electrode material 100 of the present invention has lithium halide 150 inside the pores 110a of the porous carbon material 110.
  • an ion conduction path advantageous for the movement of lithium ions can be constructed in the positive electrode active material 120, and lithium ions can be efficiently introduced into the pores 110a of the porous carbon material 110 via the lithium halide 150. sell.
  • On the surface of the positive electrode active material 120 located deep within the pores 110a not only electrons can smoothly enter and exit through the porous carbon material 110, but also lithium ions can smoothly enter and exit from the solid electrolyte 130 through the lithium halide 150.
  • the positive electrode material 100 of the present invention a reaction occurs in which the positive electrode active material 120, lithium halide 150, and the porous carbon material 110 coexist not only on the surface of the porous carbon material 110 but also inside the pores 110a. A region is formed in which the electrode reaction can proceed sufficiently.
  • the positive electrode active material 120 present inside the pores 110a can also be used as an active material for electrode reactions, and it is considered that the internal resistance of the battery is sufficiently reduced.
  • the charge/discharge reaction of a battery using a general cathode material containing sulfur is expressed as shown in equation (1) below
  • the charge/discharge reaction of a battery using the cathode material of the present invention is expressed as the following formula (2). That is, it is considered that formula (2) has more electrons involved in the reaction, so the exchange of electrons is promoted, the reaction of sulfur is promoted, and the battery reaction can proceed more efficiently.
  • the positive electrode material according to this embodiment it is preferable that more lithium halide exists inside the pores than outside the pores of the porous carbon material (that is, on the surface of the particles of the porous carbon material). By doing so, a conduction path for lithium ions can be constructed more advantageously in the positive electrode material, so that the internal resistance of the battery can be further reduced.
  • the porous carbon material in X-ray diffraction measurement using CuK ⁇ rays of the positive electrode material, between the two strongest peaks among the peaks attributed to lithium halide, the porous carbon material, It is preferable that there be a crystal peak that is not assigned to either the sulfur-containing positive electrode active material or lithium halide. That is, it is preferable that a new peak not assigned to any of the raw materials (starting materials) exists. Although the details are unknown, it is thought that the crystal structure that gives this new peak works favorably for ion movement and contributes to reducing resistance.
  • the content of lithium halide is, for example, 4% by mass or more, and preferably 5% by mass or more and less than 50% by mass, based on the total mass of the positive electrode material.
  • the content of lithium halide is within the above range, a sufficient resistance reduction effect can be easily obtained.
  • the content of lithium halide is 5 to 30% by mass, still more preferably 10 to 30% by mass, and even more preferably 20 to 30% by mass. Note that when two or more types of lithium halides are used in combination, the total amount is preferably within the above range.
  • a high-performance battery can be obtained since a sufficient amount of positive electrode active material can be secured.
  • the mass ratio of the sulfur-containing positive electrode active material and the porous carbon material is not particularly limited, but for example, the ratio (sulfur-containing positive electrode active material/porous carbon material) is 0.5. -10, preferably 2-8. Within the above range, the effects of the present invention can be obtained even more significantly.
  • the solid electrolyte is not filled inside the pores of the porous carbon material.
  • solid electrolytes are highly reactive with moisture. Therefore, when handling the solid electrolyte, an environment without exposure to the atmosphere, for example, an environment with a low dew point (dew point ⁇ -60° C.) is required, and it is necessary to use a glove box or a super dry room.
  • the positive electrode material of this embodiment provides an ion conduction path that is advantageous for the movement of lithium ions even when a solid electrolyte is not used. can be constructed.
  • the solid electrolyte content is preferably 3% by mass or less, more preferably 2% by mass or less. It is preferably 1% by mass or less, more preferably 0% by mass or less, and most preferably 0% by mass.
  • the positive electrode material of this embodiment it is preferable that only the positive electrode active material containing sulfur and lithium halide are filled inside the pores of the porous carbon material. By doing so, the effects of the present invention can be more significantly obtained.
  • the total content of the sulfur-containing positive electrode active material and lithium halide among the components filled inside the pores of the porous carbon material is 95% by mass. It is preferably 99% by mass or more, more preferably 100% by mass.
  • the method for manufacturing the positive electrode material according to this embodiment having the above configuration is not particularly limited, but the following (Manufacturing method 1) or (Manufacturing method 2) can be preferably used.
  • (manufacturing method 1) is more effective in reducing reaction resistance.
  • Manufacturing method 1 In manufacturing method 1, first, lithium halide is introduced into the pores of a porous carbon material by solution impregnation. Next, the porous carbon material having the obtained lithium halide inside the pores is further thermally impregnated with a positive electrode active material containing sulfur, and is placed inside the pores of the porous carbon material. Specifically, first, a solution in which lithium halide is dissolved in a solvent is prepared, and a porous carbon material is dispersed therein to obtain a dispersion liquid.
  • solvents examples include water; alcohols such as methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, glycerin, caprylic alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, and linolyl alcohol; and ethers such as diethyl ether, tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane. Since the solubility of lithium halide is high, water or alcohols are preferable as the solvent, and alcohols are more preferable. Thereafter, after removing the solvent, heat treatment is performed at a temperature of about 150 to 250° C. for about 1 to 5 hours.
  • alcohols such as methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, glycerin, caprylic alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol,
  • a porous carbon material whose pores are impregnated with lithium halide is obtained.
  • a porous carbon material whose pores are impregnated with lithium halide is dry mixed with a positive electrode active material, and further heat-treated under the same conditions as above.
  • the positive electrode active material melts and penetrates into the pores of the porous carbon material, creating a composite material in which the positive electrode active material is placed (filled) together with lithium halide inside the pores of the porous carbon material. positive electrode material can be obtained.
  • Manufacturing method 2 In manufacturing method 2, first, a positive electrode active material containing sulfur is introduced into the pores of a porous carbon material by thermal impregnation. Next, the porous carbon material having the obtained positive electrode active material inside the pores is further impregnated with a solution of lithium halide and placed inside the pores of the porous carbon material. Specifically, first, the porous carbon material is dry mixed with the positive electrode active material, and then heat treated at a temperature of about 150 to 250° C. for about 1 to 5 hours. As a result, a porous carbon material whose pores are impregnated with the positive electrode active material is obtained.
  • a solution of lithium halide dissolved in a solvent is prepared, and a porous carbon material whose pores are impregnated with a positive electrode active material is dispersed therein to obtain a dispersion.
  • the solvent are the same as above.
  • heat treatment is performed under the same conditions as above. Thereby, it is possible to obtain a positive electrode material as a composite material in which the positive electrode active material is arranged (filled) together with lithium halide inside the pores of the porous carbon material.
  • the pore diameter of the porous carbon material is nanoscale, simply mechanically mixing lithium halide and the porous carbon material in a solid state will not cause halogenation inside the pores of the porous carbon material. Lithium cannot be placed. In this case, the lithium halide only adheres to the surface of the particles of the porous carbon material. Similarly, even if lithium halide and a porous carbon material thermally impregnated with a positive electrode active material are mechanically mixed in a solid state, lithium halide cannot be introduced into the pores of the porous carbon material. I can't. Furthermore, the positive electrode active material cannot be introduced into the pores of the porous carbon material only by mechanical mixing in the solid state.
  • the content of the positive electrode active material in the positive electrode active material layer is not particularly limited, but for example, it is preferably within the range of 35 to 99% by mass, and preferably within the range of 40 to 90% by mass. More preferred. Note that this content value is calculated based on the mass of only the positive electrode active material, excluding the porous carbon material and lithium halide from the positive electrode material.
  • the positive electrode active material layer may further include a conductive additive (one that does not hold the positive electrode active material or solid electrolyte inside the pores) and/or a binder, and the specific forms and preferred forms of these are as follows. , those explained in the section of the negative electrode active material layer mentioned above can be similarly adopted.
  • the positive electrode active material layer preferably further includes a solid electrolyte, and particularly preferably further includes a sulfide solid electrolyte.
  • the specific form and preferred form of the solid electrolyte such as the sulfide solid electrolyte, those explained in the section of the negative electrode active material layer described above can be similarly adopted.
  • the thickness of the positive electrode active material layer varies depending on the configuration of the intended secondary battery, but is preferably within the range of 0.1 to 1000 ⁇ m, for example.
  • the material constituting the current collector plates (25, 27) is not particularly limited, and known highly conductive materials conventionally used as current collector plates for secondary batteries may be used.
  • As the constituent material of the current collector plate for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable. From the viewpoints of light weight, corrosion resistance, and high conductivity, aluminum and copper are more preferred, and aluminum is particularly preferred.
  • the positive electrode current collector plate 27 and the negative electrode current collector plate 25 may use the same material or different materials.
  • the current collector and the current collecting plate may be electrically connected via a positive electrode lead or a negative electrode lead.
  • materials used in known lithium secondary batteries can be similarly adopted.
  • the parts taken out from the exterior are covered with heat-resistant insulating heat-shrinkable material to prevent them from contacting peripheral equipment or wiring and causing electrical leakage, which may affect products (e.g., automobile parts, especially electronic equipment, etc.).
  • it is covered with a tube or the like.
  • the battery exterior material As the battery exterior material, a well-known metal can case can be used, or a bag-shaped case using a laminate film 29 containing aluminum that can cover the power generation element as shown in FIGS. 1 and 2 can be used. It can be done.
  • the laminate film may be, for example, a laminate film having a three-layer structure in which polypropylene (PP), aluminum, and nylon are laminated in this order, but is not limited thereto. It is desirable that the exterior material be a laminate film from the viewpoint that it has excellent high output and cooling performance and can be suitably used in batteries for large equipment such as EVs and HEVs. Moreover, it is more preferable that the exterior material is a laminate film containing aluminum, since the group pressure applied to the power generation element from the outside can be easily adjusted.
  • the stacked battery according to this embodiment has a configuration in which a plurality of cell layers are connected in parallel, and thus has high capacity and excellent cycle durability. Therefore, the stacked battery according to this embodiment is suitably used as a power source for driving EVs and HEVs.
  • bipolar batteries which include a bipolar electrode with a bonded negative active material layer.
  • the secondary battery according to this embodiment does not need to be an all-solid-state type. That is, the solid electrolyte layer may further contain a conventionally known liquid electrolyte (electrolyte solution).
  • a conventionally known liquid electrolyte electrolyte solution
  • the amount of liquid electrolyte (electrolyte) that can be included in the solid electrolyte layer is no particular limit to the amount of liquid electrolyte (electrolyte) that can be included in the solid electrolyte layer, but it is sufficient to maintain the shape of the solid electrolyte layer formed by the solid electrolyte and to prevent leakage of the liquid electrolyte (electrolyte). It is preferable that the amount is .
  • the present invention includes the following aspects and forms: 1. a porous carbon material, a positive electrode active material containing sulfur, and a lithium halide, wherein at least a portion of the positive electrode active material and at least a portion of the lithium halide are present in the pores of the porous carbon material. a positive electrode material, characterized in that it is disposed within; 2. In X-ray diffraction measurement, a crystalline peak that is not assigned to any of the porous carbon material, the positive electrode active material, and the lithium halide is located between the two strongest peaks assigned to the lithium halide. 1. The positive electrode material described in; 3. 1. The content of the lithium halide is 5% by mass or more and less than 50% by mass. or 2. The positive electrode material described in; 4. 1.
  • the lithium halide is present more inside the pores than outside the pores of the porous carbon material.
  • a secondary battery comprising the positive electrode material according to any one of the above.
  • Example 1 Preparation of positive electrode material
  • a glove box with an argon atmosphere with a dew point of -68°C or less add 1.0 g of lithium iodide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., LiI) to 33 mL of super dehydrated ethanol (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.).
  • LiI was dissolved in ethanol by stirring until the solution became clear.
  • porous carbon material powder manufactured by Toyo Tanso Co., Ltd., Knobel (registered trademark) P(3)010
  • the container containing this dispersion liquid was connected to a vacuum device, and while the dispersion liquid in the container was stirred by a magnetic stirrer, the pressure inside the container was reduced to 1 Pa or less using an oil rotary pump. Since the solvent ethanol evaporates under reduced pressure, the ethanol was removed over time and the porous carbon material impregnated with LiI remained in the container. After ethanol was removed under reduced pressure in this way, the material was heated to 180° C. under reduced pressure and heat treated for 3 hours to prepare a LiI-impregnated porous carbon material.
  • the average pore diameter of the porous carbon material used in this example was measured by nitrogen adsorption/desorption measurement before the above-mentioned treatment was performed.
  • This nitrogen adsorption/desorption measurement was performed using BELSORP mini manufactured by Microtrac Bell Co., Ltd., and was performed at a temperature of -196° C. using a multi-point method.
  • the BET specific surface area was determined by the multi-point method from the adsorption isotherm in the relative pressure range of 0.01 ⁇ P/P 0 ⁇ 0.05.
  • the total pore volume was determined from the volume of adsorbed N2 at a relative pressure of 0.96.
  • Pore size distribution was measured according to the BJH method.
  • the pore size distribution in the pore size range of 1 to 100 nm was measured according to the BJH method, and the pore volume of the pores in the pore size range of 1 to 4 nm was measured. When the percentage to the volume was calculated, it was 9%.
  • the powder particles of the positive electrode material were flaked to a thickness of about 100 nm using a plasma focused ion beam processing device (Helios G4 PFIB CXe manufactured by Thermo Scientific, accelerating voltage: 30 kV).
  • a plasma focused ion beam processing device Helios G4 PFIB CXe manufactured by Thermo Scientific, accelerating voltage: 30 kV.
  • the exfoliated observation sample is transported into a TEM device (manufactured by JEOL, multifunctional analytical transmission electron microscope JEM-F200, accelerating voltage: 200 kV) without being exposed to the atmosphere, and the microstructure is confirmed, and the EDX attached to the TEM is Element map data of the part corresponding to the inside of the particle was obtained using a device (energy dispersive X-ray spectrometer, Dual SDD manufactured by JEOL, accelerating voltage: 200 kV) (characteristic X-ray measurement energy band of EDX mapping: 0 to 5 keV) ). It was confirmed from the obtained elemental map data that sulfur and lithium iodide were arranged inside the pores of the porous carbon material.
  • iodine or sulfur was used as a marker element to determine whether the pores of the porous carbon material were filled with lithium iodide or the positive electrode active material. It was also confirmed that more lithium iodide was arranged inside the pores of the porous carbon material than outside the pores. Note that lithium iodide can be detected using either iodine or lithium as a labeling element.
  • FIG. 4 shows the XRD spectrum of the positive electrode material obtained in this example.
  • the XRD spectrum of a sample obtained by thermally impregnating only elemental sulfur into a porous carbon material using the same method as above and the XRD spectrum of LiI are also shown.
  • a new peak (indicated by an arrow) not assigned to any of the starting materials was observed between the two strongest peaks indicated by ⁇ among the peaks assigned to LiI. Ta.
  • test cell all-solid lithium secondary battery
  • the battery was manufactured in a glove box in an argon atmosphere with a dew point of -68°C or lower.
  • test cell all solid lithium secondary battery
  • Example 2 Preparation of positive electrode material
  • sulfur manufactured by Aldrich
  • porous carbon material powder manufactured by Toyo Tanso Co., Ltd., Knobel (registered trademark) P (manufactured by Toyo Tanso Co., Ltd.) 3
  • the mixed powder is placed in a sealed pressure-resistant autoclave container and heated at 170°C for 3 hours to melt the sulfur and turn the sulfur into a porous carbon material. Impregnated. In this way, a sulfur-impregnated porous carbon material was prepared.
  • the container containing this dispersion liquid was connected to a vacuum device, and while the dispersion liquid in the container was stirred by a magnetic stirrer, the pressure inside the container was reduced to 1 Pa or less using an oil rotary pump. Since ethanol, which is a solvent, evaporates under reduced pressure, ethanol was removed over time, and a porous carbon material whose pores were filled with sulfur and LiI remained in the container. After ethanol was removed under reduced pressure in this way, a positive electrode material was prepared by heating to 180° C. under reduced pressure and performing heat treatment for 3 hours.
  • Example 2 An all-solid-state lithium secondary battery was produced by the same method as in Example 1 except for the above.
  • Example 5 An all-solid-state lithium secondary battery was produced in the same manner as in Example 1 above, except that ultra-dehydrated ethanol was replaced with ultra-pure water in preparing the positive electrode material.
  • Example 6 An all-solid-state lithium secondary battery was produced in the same manner as in Example 1, except that lithium iodide was replaced with lithium chloride (LiCl) in preparing the positive electrode material.
  • the XRD spectrum of the positive electrode material obtained in Example 6 was measured in the same manner as above. The results are shown in Figure 5. For comparison, the XRD spectrum of a sample in which a porous carbon material was thermally impregnated with only elemental sulfur and the XRD spectrum of LiCl are also shown. In the positive electrode material obtained in Example 6, a new peak (indicated by an arrow) not assigned to any of the starting materials was observed between the two strongest peaks indicated by ⁇ among the peaks assigned to LiCl. Ta.
  • Example 7 An all-solid-state lithium secondary battery was produced in the same manner as in Example 1, except that lithium bromide (LiBr) was used instead of lithium iodide in the preparation of the positive electrode material.
  • the positive electrode material prepared in Example 7 it was confirmed by TEM-EDX measurement similar to the above that sulfur and lithium bromide were arranged inside the pores of the porous carbon material. It was also confirmed that more lithium bromide was arranged inside the pores of the porous carbon material than outside the pores. Furthermore, the XRD spectrum of the positive electrode material obtained in Example 7 was measured in the same manner as above. In the positive electrode material obtained in Example 7, a new peak that was not assigned to any of the starting materials was observed between the two strongest peaks among the peaks assigned to LiBr in the XRD spectrum.
  • Example 8 An all-solid-state lithium secondary battery was produced in the same manner as in Example 1, except that lithium iodide was replaced with lithium fluoride (LiF) in preparing the positive electrode material.
  • the positive electrode material prepared in Example 8 it was confirmed by TEM-EDX measurement similar to the above that sulfur and lithium fluoride were arranged inside the pores of the porous carbon material. It was also confirmed that more lithium fluoride was arranged inside the pores of the porous carbon material than outside the pores. Furthermore, the XRD spectrum of the positive electrode material obtained in Example 8 was measured in the same manner as above. In the positive electrode material obtained in Example 8, a new peak that was not assigned to any of the starting materials was observed between the two strongest peaks among the peaks assigned to LiF in the XRD spectrum.
  • lithium iodide was present outside the pores of the porous carbon material and was not located inside the pores.
  • the XRD spectrum of the positive electrode material obtained in Comparative Example 1 was measured in the same manner as above. The results are shown in FIG. For comparison, the XRD spectrum of elemental sulfur and the XRD spectrum of the positive electrode material of Example 1 are also shown. In the positive electrode material of Comparative Example 1, peaks derived from starting materials such as elemental sulfur and LiI were observed, but no new peak between the two strongest peaks attributed to LiI was observed. Ta.
  • An all-solid lithium secondary battery was produced by the same method as in Example 1 except for the above.
  • lithium chloride was present outside the pores of the porous carbon material and was not arranged inside the pores.
  • the XRD spectrum of the positive electrode material obtained in Comparative Example 2 was measured in the same manner as above. The results are shown in FIG. For comparison, the XRD spectrum of elemental sulfur and the XRD spectrum of the positive electrode material of Example 6 are also shown. In the positive electrode material of Comparative Example 2, peaks derived from starting materials such as elemental sulfur and LiCl were observed, but no new peak between the two strongest peaks attributed to LiCl was observed. Ta.
  • test cell The resistance values of the test cells prepared in each of the comparative examples and examples described above were measured by the method described below. All of the following measurements were performed using a charge/discharge test device (manufactured by Hokuto Denko Co., Ltd., HJ-SD8) in a constant temperature bath set at 25°C.
  • Table 1 show that according to the positive electrode material of the present invention, the internal resistance of a secondary battery using a positive electrode active material containing sulfur can be further reduced.
  • 10a Stacked battery 11' negative electrode current collector, 11" positive electrode current collector, 13 negative electrode active material layer, 15 positive electrode active material layer, 17 solid electrolyte layer, 19 unit cell layer, 21 power generation element, 25 negative electrode current collector plate , 27 positive electrode current collector plate, 29 laminate film, 100, 100' positive electrode material, 110 porous carbon material, 110a pores, 120 positive electrode active material containing sulfur, 130 solid electrolyte, 140 area near the interface, 150 lithium halide .

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PCT/IB2023/000145 2022-03-31 2023-03-24 正極材料およびこれを用いた二次電池 Ceased WO2023187466A1 (ja)

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CN202380030846.7A CN118946984A (zh) 2022-03-31 2023-03-24 正极材料和使用了其的二次电池
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WO2026019021A1 (ko) * 2024-07-15 2026-01-22 삼성에스디아이 주식회사 양극 활물질, 이를 포함하는 양극 및 전고체 전지

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2026019021A1 (ko) * 2024-07-15 2026-01-22 삼성에스디아이 주식회사 양극 활물질, 이를 포함하는 양극 및 전고체 전지

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CN118946984A (zh) 2024-11-12
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