WO2022168845A1 - Nonaqueous electrolyte power storage element and power storage device - Google Patents

Nonaqueous electrolyte power storage element and power storage device Download PDF

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WO2022168845A1
WO2022168845A1 PCT/JP2022/003949 JP2022003949W WO2022168845A1 WO 2022168845 A1 WO2022168845 A1 WO 2022168845A1 JP 2022003949 W JP2022003949 W JP 2022003949W WO 2022168845 A1 WO2022168845 A1 WO 2022168845A1
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positive electrode
aqueous electrolyte
lithium
negative electrode
compound
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PCT/JP2022/003949
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French (fr)
Japanese (ja)
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祐輝 酒井
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株式会社Ｇｓユアサ
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/54—Electrolytes
    • H01G11/58—Liquid electrolytes
    • H01G11/62—Liquid electrolytes characterised by the solute, e.g. salts, anions or cations therein
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers

Definitions

  • the present invention relates to non-aqueous electrolyte power storage elements and power storage devices.
  • Non-aqueous electrolyte secondary batteries typified by lithium-ion secondary batteries
  • the non-aqueous electrolyte secondary battery generally has a pair of electrodes electrically isolated by a separator and a non-aqueous electrolyte interposed between the electrodes, and transfers ions between the electrodes. It is configured to be charged and discharged by Capacitors such as lithium ion capacitors and electric double layer capacitors are also widely used as non-aqueous electrolyte storage elements other than non-aqueous electrolyte secondary batteries.
  • Patent Document 1 discloses a lithium secondary battery using a lithium metal foil as a negative electrode.
  • the lithium secondary battery using lithium metal for the negative electrode disclosed in the above patent document has a high energy density, but there is a risk that the internal resistance will increase with charge-discharge cycles, and the surface of the negative electrode during charging.
  • Lithium metal may be deposited in a dendritic form (hereinafter, lithium metal in a dendritic form is referred to as "dendrite”), and this dendrite deposition may cause an internal short circuit.
  • An object of the present invention is to provide a non-aqueous electrolyte storage element and a storage device that have high energy density, can suppress an increase in internal resistance due to charge/discharge cycles, and can delay the occurrence of an internal short circuit. It is to be.
  • a non-aqueous electrolyte storage element includes a positive electrode having a positive electrode mixture containing a phosphorus element, a negative electrode containing lithium metal, and a non-aqueous electrolyte containing a compound a, wherein the compound a is an oxygen element. , elemental fluorine, and at least one of elemental phosphorus and elemental boron.
  • Another aspect of the present invention is a power storage device including two or more non-aqueous electrolyte storage elements and one or more non-aqueous electrolyte storage elements according to another aspect of the present invention.
  • the non-aqueous electrolyte power storage element and the power storage device according to one aspect of the present invention have high energy density, can suppress an increase in internal resistance due to charge-discharge cycles, and can delay the occurrence of an internal short circuit. be.
  • FIG. 1 is a see-through perspective view showing one embodiment of a non-aqueous electrolyte storage element.
  • FIG. 2 is a schematic diagram showing an embodiment of a power storage device configured by assembling a plurality of non-aqueous electrolyte power storage elements.
  • a non-aqueous electrolyte storage element includes a positive electrode having a positive electrode mixture containing a phosphorus element, a negative electrode containing lithium metal, and a non-aqueous electrolyte containing a compound a, wherein the compound a is an oxygen element. , elemental fluorine, and at least one of elemental phosphorus and elemental boron.
  • the non-aqueous electrolyte storage element has a high energy density, can suppress an increase in internal resistance due to charge-discharge cycles, and can delay the occurrence of an internal short circuit.
  • the reason for this is presumed to be as follows. Since the non-aqueous electrolyte storage element includes a negative electrode containing lithium metal, the energy density is high. In a conventional non-aqueous electrolyte storage element having a negative electrode containing lithium metal, the decomposition of the non-aqueous electrolyte is significantly accelerated on the surface of the negative electrode, so that the ionic conductivity of the non-aqueous electrolyte is greatly reduced.
  • the decomposition tends to increase the thickness of the film formed on the surface of the negative electrode, and the ionic conductivity of the surface of the negative electrode decreases. As a result, the internal resistance tends to increase. In addition, the film is unevenly formed, causing localized current concentration at the negative electrode, which facilitates dendrite deposition of lithium metal on the surface of the negative electrode during charging, and as a result, tends to cause an internal short circuit.
  • the compound a contained in the non-aqueous electrolyte reacts with the lithium metal of the negative electrode preferentially over other components of the non-aqueous electrolyte, and the negative electrode surface is derived from the compound a.
  • the coating film derived from compound a in the negative electrode can suppress decomposition of other components of the non-aqueous electrolyte.
  • the film derived from compound a has relatively high ionic conductivity because it is derived from compound a having the composition described above.
  • the film derived from the compound a is easily formed uniformly, and local current concentration in the negative electrode can be suppressed.
  • the positive electrode of the non-aqueous electrolyte storage element has a positive electrode mixture containing phosphorus element, the positive electrode film is formed from the phosphorus element by the reaction between the positive electrode mixture and the non-aqueous electrolyte.
  • the phosphorus element-derived film on the positive electrode suppresses the decomposition of the non-aqueous electrolyte on the positive electrode surface and contributes to the selective reaction of the compound a contained in the non-aqueous electrolyte on the negative electrode surface. Therefore, the presence of the film derived from phosphorus on the positive electrode facilitates the formation of the film derived from the compound a on the negative electrode more uniformly and satisfactorily.
  • the action of the phosphorus element contained in the positive electrode mixture and the compound a contained in the non-aqueous electrolyte It is thought that good coatings are formed on both the positive and negative electrodes, and as a result, dendrite precipitation, which causes an increase in internal resistance and an internal short circuit, is effectively reduced.
  • the compound a may be lithium difluorophosphate (LiDFP) or lithium difluorooxalate borate (LiDFOB).
  • LiDFP lithium difluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • the peak position of P2p may be 135 eV or less.
  • the P2p peak appearing below 135 eV in the above spectrum is the peak of a phosphorus atom derived from a phosphorus oxoacid such as phosphonic acid. That is, it indicates that phosphorus atoms derived from the oxoacid of phosphorus are present on the surface of the positive electrode mixture, and that a film containing the phosphorus atoms is formed on the surface of the positive electrode.
  • the film containing the phosphorus atoms is formed on the surface of the positive electrode in this way, the decomposition of the non-aqueous electrolyte on the surface of the positive electrode is further suppressed.
  • the formation of the film containing the phosphorus atom on the positive electrode makes it easier for the compound a to react more selectively on the surface of the negative electrode than on the surface of the positive electrode, so that the film derived from the compound a on the negative electrode is more uniform and good. easy to form.
  • a sample used for measuring the spectrum of the positive electrode mixture by X-ray photoelectron spectroscopy (XPS) is prepared by the following method.
  • the non-aqueous electrolyte storage element is discharged with a current of 0.1 C to the final discharge voltage in normal use, and is placed in a discharged state.
  • “during normal use” refers to the case where the non-aqueous electrolyte storage element is used under discharge conditions recommended or specified for the non-aqueous electrolyte storage element.
  • the discharged non-aqueous electrolyte storage element is disassembled, the positive electrode is taken out, the positive electrode is thoroughly washed with dimethyl carbonate, and then dried under reduced pressure at room temperature.
  • the dried positive electrode is cut into a predetermined size (for example, 2 ⁇ 2 cm 2 ) and used as a sample for spectrum measurement by XPS.
  • the work from the dismantling of the non-aqueous electrolyte storage element to the preparation of the sample for spectral measurement by XPS was performed in an argon atmosphere with a dew point of -60°C or less, and the sample was enclosed in a transfer vessel and was not exposed to the atmosphere.
  • the equipment used and the measurement conditions in XPS spectrum measurement of the positive electrode mixture are as follows.
  • the P2p peak position in the above spectrum is a value obtained as follows. First, the binding energy of the sp2 carbon peak in C1s is set to 284.8 eV, and all spectra obtained are corrected. Each spectrum is then smoothed by subtracting the background using the linear method. The binding energy showing the highest peak intensity in the range of 130 to 138 eV in the spectrum after flattening is defined as the P2p peak position.
  • the configuration of the non-aqueous electrolyte storage element the configuration of the storage device, the method for manufacturing the non-aqueous electrolyte storage element, and other embodiments according to one embodiment of the present invention will be described in detail. Note that the name of each component (each component) used in each embodiment may be different from the name of each component (each component) used in the background art.
  • a non-aqueous electrolyte storage element includes an electrode body having a positive electrode, a negative electrode and a separator, a non-aqueous electrolyte, the electrode body and the non-aqueous electrolyte and a container that houses the
  • the electrode body is usually a laminated type in which a plurality of positive electrodes and a plurality of negative electrodes are laminated with separators interposed therebetween, or a wound type in which positive electrodes and negative electrodes are laminated with separators interposed and wound.
  • the non-aqueous electrolyte exists in a state contained in the positive electrode, the negative electrode and the separator.
  • a non-aqueous electrolyte secondary battery hereinafter also simply referred to as "secondary battery" will be described.
  • the positive electrode has a positive electrode base material and a positive electrode material mixture layer disposed on the positive electrode base material directly or via an intermediate layer.
  • a positive electrode base material has electroconductivity. Whether or not a material has “conductivity” is determined using a volume resistivity of 10 7 ⁇ cm as a threshold measured according to JIS-H-0505 (1975).
  • the material for the positive electrode substrate metals such as aluminum, titanium, tantalum and stainless steel, or alloys thereof are used. Among these, aluminum or an aluminum alloy is preferable from the viewpoint of potential resistance, high conductivity, and cost.
  • Examples of the positive electrode substrate include foil, deposited film, mesh, porous material, and the like, and foil is preferable from the viewpoint of cost. Therefore, aluminum foil or aluminum alloy foil is preferable as the positive electrode substrate. Examples of aluminum or aluminum alloys include A1085, A3003, A1N30, etc. defined in JIS-H-4000 (2014) or JIS-H4160 (2006).
  • the average thickness of the positive electrode substrate is preferably 3 ⁇ m or more and 50 ⁇ m or less, more preferably 5 ⁇ m or more and 40 ⁇ m or less, even more preferably 8 ⁇ m or more and 30 ⁇ m or less, and particularly preferably 10 ⁇ m or more and 25 ⁇ m or less.
  • the intermediate layer is a layer arranged between the positive electrode substrate and the positive electrode material mixture layer.
  • the intermediate layer contains a conductive agent such as carbon particles to reduce the contact resistance between the positive electrode substrate and the positive electrode mixture layer.
  • the composition of the intermediate layer is not particularly limited, and includes, for example, a binder and a conductive agent.
  • the positive electrode mixture layer is a layer formed of a positive electrode mixture.
  • This positive electrode mixture contains a phosphorus element.
  • the positive electrode mixture further contains a positive electrode active material, and optionally other optional components such as a conductive agent, a binder (binder), a thickener, and a filler.
  • the positive electrode material mixture layer is usually formed on the surface of the positive electrode substrate by coating and drying a positive electrode material mixture paste.
  • the positive electrode active material can be appropriately selected from known positive electrode active materials.
  • positive electrode active materials for lithium secondary batteries include lithium transition metal composite oxides having a ⁇ -NaFeO 2 type crystal structure, lithium transition metal composite oxides having a spinel crystal structure, polyanion compounds, chalcogen compounds, sulfur etc.
  • lithium transition metal composite oxides having an ⁇ -NaFeO 2 type crystal structure examples include Li[Li x Ni (1-x) ]O 2 (0 ⁇ x ⁇ 0.5), Li[Li x Ni ⁇ Co ( 1-x- ⁇ ) ]O 2 (0 ⁇ x ⁇ 0.5, 0 ⁇ 1), Li[Li x Co (1-x) ]O 2 (0 ⁇ x ⁇ 0.5), Li[ Li x Ni ⁇ Mn (1-x- ⁇ ) ]O 2 (0 ⁇ x ⁇ 0.5, 0 ⁇ 1), Li[Li x Ni ⁇ Mn ⁇ Co (1-x- ⁇ - ⁇ ) ] O 2 (0 ⁇ x ⁇ 0.5, 0 ⁇ , 0 ⁇ , 0.5 ⁇ + ⁇ 1), Li[Li x Ni ⁇ Co ⁇ Al (1-x- ⁇ - ⁇ ) ]O 2 ( 0 ⁇ x ⁇ 0.5, 0 ⁇ , 0 ⁇ , 0.5 ⁇ + ⁇ 1) and the like.
  • lithium transition metal composite oxides having a spinel crystal structure examples include Li x Mn 2 O 4 and Li x Ni ⁇ Mn (2- ⁇ ) O 4 .
  • polyanion compounds include LiFePO4 , LiMnPO4 , LiNiPO4 , LiCoPO4, Li3V2(PO4)3 , Li2MnSiO4 , Li2CoPO4F and the like.
  • chalcogen compounds include titanium disulfide, molybdenum disulfide, and molybdenum dioxide.
  • the atoms or polyanions in these materials may be partially substituted with atoms or anionic species of other elements. These materials may be coated with other materials on their surfaces. In the positive electrode mixture layer, one kind of these materials may be used alone, or two or more kinds may be mixed and used.
  • the positive electrode active material is usually particles (powder).
  • the average particle size of the positive electrode active material is preferably, for example, 0.1 ⁇ m or more and 20 ⁇ m or less. By making the average particle diameter of the positive electrode active material equal to or more than the above lower limit, the production or handling of the positive electrode active material becomes easy. By making the average particle size of the positive electrode active material equal to or less than the above upper limit, the electron conductivity of the positive electrode mixture layer is improved. Note that when a composite of a positive electrode active material and another material is used, the average particle size of the composite is taken as the average particle size of the positive electrode active material.
  • Average particle size is based on JIS-Z-8825 (2013), based on the particle size distribution measured by a laser diffraction / scattering method for a diluted solution in which particles are diluted with a solvent, JIS-Z-8819 -2 (2001) means a value at which the volume-based integrated distribution calculated according to 50%.
  • Pulverizers, classifiers, etc. are used to obtain powder with a predetermined particle size.
  • Pulverization methods include, for example, methods using a mortar, ball mill, sand mill, vibrating ball mill, planetary ball mill, jet mill, counter jet mill, whirling jet mill, or sieve.
  • wet pulverization in which water or an organic solvent such as hexane is allowed to coexist can also be used.
  • a sieve, an air classifier, or the like is used as necessary, both dry and wet.
  • the content of the positive electrode active material in the positive electrode mixture layer is preferably 50% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 98% by mass or less, and even more preferably 80% by mass or more and 95% by mass or less.
  • the elemental phosphorus contained in the positive electrode mixture is preferably present in the positive electrode mixture in the form of a phosphorus oxoacid or a derivative obtained from the phosphorus oxoacid. That is, the positive electrode mixture preferably contains a phosphorus oxoacid or a derivative thereof.
  • Examples of the phosphorus oxoacid include phosphoric acid (H 3 PO 4 ), phosphonic acid (H 3 PO 3 ), phosphinic acid (H 3 PO 2 ), pyrophosphoric acid (H 4 P 2 O 7 ), polyphosphoric acid, and the like. Among these, phosphonic acid is more preferable.
  • Derivatives obtained from the above phosphorus oxoacids include phosphorus oxoacid salts and phosphorus oxoacid esters. In this way, when the positive electrode mixture contains the oxoacid of phosphorus or a derivative thereof, a favorable film containing phosphorus atoms is easily formed on the surface of the positive electrode. In addition, the formation of the film containing the phosphorus atoms on the surface of the positive electrode promotes uniform and favorable film formation derived from the compound a on the negative electrode.
  • the peak position of P2p is preferably 135 eV or less.
  • the peak position is preferably 131 eV or higher, more preferably 132 eV or higher, and even more preferably 133 eV or higher.
  • the P2p peaks appearing in the above range are peaks of phosphorus atoms derived from phosphorus oxoacids such as phosphonic acid. That is, the P2p peak indicates that phosphorus atoms derived from the oxoacid of phosphorus exist on the surface of the positive electrode mixture, and the phosphorus atoms form a film on the surface of the positive electrode.
  • the film containing the phosphorus atoms on the surface of the positive electrode in this way, decomposition of the non-aqueous electrolyte on the surface of the positive electrode is further suppressed.
  • the formation of such a coating promotes uniform and good coating formation on the negative electrode.
  • a P2p peak outside the above range may be present.
  • the P2p peak appearing in the range of binding energy of 135 eV or more is the peak of phosphorus atoms derived from, for example, fluoride of phosphorus.
  • the conductive agent is not particularly limited as long as it is a conductive material.
  • Examples of such conductive agents include carbonaceous materials, metals, and conductive ceramics.
  • Carbonaceous materials include graphite, non-graphitic carbon, graphene-based carbon, and the like.
  • Examples of non-graphitic carbon include carbon nanofiber, pitch-based carbon fiber, and carbon black.
  • Examples of carbon black include furnace black, acetylene black, and ketjen black.
  • Graphene-based carbon includes graphene, carbon nanotube (CNT), fullerene, and the like.
  • the shape of the conductive agent may be powdery, fibrous, or the like.
  • As the conductive agent one type of these materials may be used alone, or two or more types may be mixed and used. Also, these materials may be combined for use.
  • a composite material of carbon black and CNT may be used.
  • carbon black is preferable from the viewpoint of electron conductivity and coatability
  • acetylene black is particularly preferable
  • the content of the conductive agent in the positive electrode mixture layer is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less.
  • Binders include, for example, fluorine resins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), thermoplastic resins such as polyethylene, polypropylene, polyacryl, and polyimide; ethylene-propylene-diene rubber (EPDM), sulfone Elastomers such as modified EPDM, styrene-butadiene rubber (SBR) and fluororubber; polysaccharide polymers and the like.
  • fluorine resins polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.
  • thermoplastic resins such as polyethylene, polypropylene, polyacryl, and polyimide
  • EPDM ethylene-propylene-diene rubber
  • SBR styrene-butadiene rubber
  • fluororubber polysaccharide polymers and the like.
  • the content of the binder in the positive electrode mixture layer is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less.
  • thickeners examples include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose.
  • CMC carboxymethylcellulose
  • methylcellulose examples include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose.
  • the functional group may be previously deactivated by methylation or the like.
  • the filler is not particularly limited.
  • Fillers include polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, alumina, titanium dioxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide and aluminosilicate, magnesium hydroxide, calcium hydroxide, hydroxide Hydroxides such as aluminum, carbonates such as calcium carbonate, poorly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium sulfate, nitrides such as aluminum nitride and silicon nitride, talc, montmorillonite, boehmite, zeolite, Mineral resource-derived substances such as apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof may be used.
  • the positive electrode mixture layer contains typical nonmetallic elements such as B, N, F, Cl, Br, and I, and typical elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, and Ba.
  • Metal elements, transition metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Nb, and W are used as positive electrode active materials, and phosphorus elements (for example, phosphorus oxoacids or derivatives thereof) , a conductive agent, a binder, a thickener, and a component other than a filler.
  • the negative electrode has a negative electrode active material layer.
  • the negative electrode may further include a negative electrode substrate and an intermediate layer interposed between the negative electrode substrate and the negative electrode active material layer.
  • the structure of the intermediate layer is not particularly limited, and can be selected from, for example, the structures exemplified for the positive electrode.
  • the negative electrode base material has conductivity.
  • materials for the negative electrode substrate metals such as copper, nickel, stainless steel, nickel-plated steel, alloys thereof, carbonaceous materials, and the like are used. Among these, stainless steel, copper, or copper alloys are preferred.
  • negative electrode substrates include foils, deposited films, meshes, porous materials, and the like, and foils are preferable from the viewpoint of cost. Therefore, stainless steel foil, copper foil, or copper alloy foil is preferable as the negative electrode substrate.
  • examples of copper foil include rolled copper foil and electrolytic copper foil.
  • the average thickness of the negative electrode substrate is preferably 2 ⁇ m or more and 35 ⁇ m or less, more preferably 3 ⁇ m or more and 30 ⁇ m or less, even more preferably 4 ⁇ m or more and 25 ⁇ m or less, and particularly preferably 5 ⁇ m or more and 20 ⁇ m or less.
  • the negative electrode active material layer contains lithium metal.
  • Lithium metal is a component that functions as a negative electrode active material.
  • Lithium metal may exist as pure lithium metal consisting essentially of the lithium element, or may exist as a lithium alloy containing other metal elements. Together they are called "lithium metal".
  • Lithium alloys include lithium gold alloys, lithium tin alloys, lithium silver alloys, lithium zinc alloys, lithium calcium alloys, lithium aluminum alloys, lithium magnesium alloys, lithium indium alloys, and the like.
  • the lithium alloy may contain multiple metal elements other than the lithium element.
  • the negative electrode active material layer may be a layer consisting essentially of lithium metal.
  • the lithium metal content in the negative electrode active material layer may be 90% by mass or more, 99% by mass or more, or 100% by mass.
  • the energy density of the secondary battery can be further increased.
  • the negative electrode active material layer may be lithium metal foil (including lithium alloy foil).
  • the negative electrode active material layer may be a non-porous layer (solid layer).
  • the average thickness of the negative electrode active material layer is preferably 5 ⁇ m or more and 600 ⁇ m or less, more preferably 10 ⁇ m or more and 400 ⁇ m or less, and even more preferably 30 ⁇ m or more and 200 ⁇ m or less. By setting the average thickness of the negative electrode active material layer within the above range, it is possible to achieve both high energy density and manufacturability of the negative electrode active material layer.
  • the separator can be appropriately selected from known separators.
  • a separator consisting of only a substrate layer, a separator having a heat-resistant layer containing heat-resistant particles and a binder formed on one or both surfaces of a substrate layer, or the like can be used.
  • Examples of the shape of the base layer of the separator include woven fabric, nonwoven fabric, and porous resin film. Among these shapes, a porous resin film is preferred from the viewpoint of strength, and a non-woven fabric is preferred from the viewpoint of non-aqueous electrolyte retention.
  • polyolefins such as polyethylene and polypropylene are preferable from the viewpoint of shutdown function, and polyimide, aramid, and the like are preferable from the viewpoint of oxidative decomposition resistance.
  • a material obtained by combining these resins may be used as the base material layer of the separator.
  • the heat-resistant particles contained in the heat-resistant layer preferably have a mass loss of 5% or less when the temperature is raised from room temperature to 500 ° C. in an air atmosphere of 1 atm, and the mass loss when the temperature is raised from room temperature to 800 ° C. is more preferably 5% or less.
  • An inorganic compound can be mentioned as a material whose mass reduction is less than or equal to a predetermined value. Examples of inorganic compounds include oxides such as iron oxide, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, and aluminosilicate; nitrides such as aluminum nitride and silicon nitride.
  • carbonates such as calcium carbonate
  • sulfates such as barium sulfate
  • sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium titanate
  • covalent crystals such as silicon and diamond
  • Mineral resource-derived substances such as zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof.
  • the inorganic compound a single substance or a composite of these substances may be used alone, or two or more of them may be mixed and used.
  • silicon oxide, aluminum oxide, or aluminosilicate is preferable from the viewpoint of the safety of the electric storage device.
  • the porosity of the separator is preferably 80% by volume or less from the viewpoint of strength, and preferably 20% by volume or more from the viewpoint of discharge performance.
  • the "porosity” is a volume-based value and means a value measured with a mercury porosimeter.
  • a polymer gel composed of a polymer and a non-aqueous electrolyte may be used as the separator.
  • examples of polymers include polyacrylonitrile, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyvinylidene fluoride, and the like.
  • the use of polymer gel has the effect of suppressing liquid leakage.
  • a polymer gel may be used in combination with the porous resin film or non-woven fabric as described above.
  • the non-aqueous electrolyte contains compound a.
  • a non-aqueous electrolyte may be used as the non-aqueous electrolyte.
  • the non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.
  • the non-aqueous electrolyte may contain additives in addition to the non-aqueous solvent and electrolyte salt.
  • the compound a may be contained as an electrolyte salt or as an additive in the non-aqueous electrolyte. At least one of the electrolyte salt and the additive contains the compound a.
  • the non-aqueous solvent can be appropriately selected from known non-aqueous solvents.
  • Non-aqueous solvents include cyclic carbonates, chain carbonates, carboxylic acid esters, phosphoric acid esters, sulfonic acid esters, ethers, amides, nitriles and the like.
  • the non-aqueous solvent those in which some of the hydrogen atoms contained in these compounds are substituted with halogens may be used.
  • Cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinylethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), difluoroethylene carbonate. (DFEC), styrene carbonate, 1-phenylvinylene carbonate, 1,2-diphenylvinylene carbonate and the like. Among these, FEC is preferred.
  • chain carbonates examples include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diphenyl carbonate, trifluoroethylmethyl carbonate (TFEMC), bis(trifluoroethyl) carbonate, and the like.
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • EMC ethylmethyl carbonate
  • TFEMC trifluoroethylmethyl carbonate
  • bis(trifluoroethyl) carbonate and the like.
  • the non-aqueous solvent it is preferable to use a cyclic carbonate or a chain carbonate, and it is more preferable to use a combination of a cyclic carbonate and a chain carbonate.
  • a cyclic carbonate it is possible to promote the dissociation of the electrolyte salt and improve the ionic conductivity of the non-aqueous electrolyte.
  • a chain carbonate By using a chain carbonate, the viscosity of the non-aqueous electrolyte can be kept low.
  • the volume ratio of the cyclic carbonate to the chain carbonate is preferably in the range of, for example, 5:95 to 50:50.
  • the electrolyte salt can be appropriately selected from known electrolyte salts.
  • electrolyte salts include lithium salts, sodium salts, potassium salts, magnesium salts, onium salts and the like. Among these, lithium salts are preferred.
  • Lithium salts include inorganic lithium salts such as LiPF 6 , lithium difluorophosphate (LiDFP), lithium monofluorophosphate, LiBF 4 , LiClO 4 , LiN(SO 2 F) 2 , and lithium bis(oxalate)borate (LiBOB).
  • LiPF 6 lithium difluorophosphate
  • LiClO 4 lithium monofluorophosphate
  • LiN(SO 2 F) 2 LiN(SO 2 F) 2
  • LiBOB lithium bis(oxalate)borate
  • lithium difluorooxalateborate LiDFOB
  • lithium difluorobis(oxalate)phosphate LiFOP
  • lithium oxalate salts such as lithium tetrafluorooxalate phosphate
  • LiSO3CF3 LiN( SO2CF3 ) 2
  • LiN Halogenated hydrocarbons such as SO2C2F5 ) 2
  • LiN ( SO2CF3 ) ( SO2C4F9 ) LiC ( SO2CF3 ) 3
  • LiC ( SO2C2F5 ) 3 LiC ( SO2C2F5 ) 3
  • lithium salt having a group LiPF6 is more preferred.
  • the lithium difluorophosphate (LiDFP), lithium monofluorophosphate, lithium difluorooxalate borate (LiDFOB), lithium difluorobis(oxalate) phosphate (LiFOP) and lithium tetrafluorooxalate phosphate are compound a as the electrolyte salt.
  • compound a may be used as an electrolyte salt.
  • the content of the electrolyte salt in the non-aqueous electrolyte is preferably 0.1 mol/dm3 or more and 2.5 mol/dm3 or less , and 0.3 mol/dm3 or more and 2.0 mol/dm3 or less at 20 °C and 1 atm. It is more preferably 3 or less, more preferably 0.5 mol/dm 3 or more and 1.7 mol/dm 3 or less, and particularly preferably 0.7 mol/dm 3 or more and 1.5 mol/dm 3 or less.
  • compound a may also be used as an additive.
  • the compound a as an additive contains oxygen element, fluorine element, and at least one of phosphorus element and boron element.
  • Examples of the compound a include a lithium phosphate containing lithium element, oxygen element and fluorine element, a lithium oxalate containing lithium element, boron element and fluorine element, and lithium element, phosphorus element and fluorine element.
  • the compound a a lithium phosphate containing lithium element, oxygen element and fluorine element is preferable from the viewpoint of delaying the occurrence of an internal short circuit.
  • the non-aqueous electrolyte contains the compound a in this way, a good film derived from the compound a is easily formed on the surface of the negative electrode.
  • the non-aqueous electrolyte may further contain other additives in addition to the compound a.
  • the other additives include halogenated carbonates such as fluoroethylene carbonate (FEC) and difluoroethylene carbonate (DFEC); oxalates such as lithium bis(oxalate)borate (LiBOB); lithium bis(fluorosulfonyl); ) imide salts such as imide (LiFSI); biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran and other aromatic compounds; 2- Partial halides of the above aromatic compounds such as fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5
  • the content of the compound a contained in the non-aqueous electrolyte is preferably 0.01% by mass or more and 10% by mass or less with respect to the total mass of the non-aqueous electrolyte, and 0.1% by mass or more and 7% by mass or less. is more preferably 0.2% by mass or more and 6% by mass or less, and particularly preferably 0.3% by mass or more and 5% by mass or less.
  • the total content of the compound a and the other additives contained in the non-aqueous electrolyte is preferably 0.01% by mass or more and 10% by mass or less with respect to the total mass of the non-aqueous electrolyte, and 0.1 It is more preferably 0.2% to 8% by mass, and particularly preferably 0.3% to 7% by mass.
  • a solid electrolyte may be used as the non-aqueous electrolyte, or a non-aqueous electrolyte and a solid electrolyte may be used together.
  • the solid electrolyte can be selected from any material that has ion conductivity, such as lithium, sodium, and calcium, and is solid at room temperature (for example, 15°C to 25°C).
  • Examples of solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, oxynitride solid electrolytes, and polymer solid electrolytes.
  • Examples of sulfide solid electrolytes for lithium secondary batteries include Li 2 SP 2 S 5 , LiI—Li 2 SP 2 S 5 , Li 10 Ge—P 2 S 12 and the like.
  • FIG. 1 shows a non-aqueous electrolyte storage element 1 as an example of a square battery. In addition, the same figure is taken as the figure which saw through the inside of a container.
  • An electrode body 2 having a positive electrode and a negative electrode wound with a separator sandwiched therebetween is housed in a rectangular container 3 .
  • the positive electrode is electrically connected to the positive electrode terminal 4 via a positive electrode lead 41 .
  • the negative electrode is electrically connected to the negative terminal 5 via a negative lead 51 .
  • the non-aqueous electrolyte storage element of the present embodiment is a power source for automobiles such as electric vehicles (EV), hybrid vehicles (HEV), and plug-in hybrid vehicles (PHEV), power sources for electronic devices such as personal computers and communication terminals, or electric power It can be installed in a power source for storage or the like as a power storage unit (battery module) configured by collecting a plurality of non-aqueous electrolyte power storage elements 1 .
  • the technology of the present invention may be applied to at least one non-aqueous electrolyte storage element included in the storage unit.
  • a power storage device includes two or more nonaqueous electrolyte power storage elements and one or more nonaqueous electrolyte power storage elements according to the above embodiments (hereinafter referred to as "second embodiment"). ). It is sufficient that the technology according to one embodiment of the present invention is applied to at least one non-aqueous electrolyte power storage element included in the power storage device according to the second embodiment.
  • One non-aqueous electrolyte storage element may be provided, and one or more non-aqueous electrolyte storage elements according to the above embodiment may be provided, and two non-aqueous electrolyte storage elements according to the above embodiment may be provided. You may have more. FIG.
  • the power storage device 30 includes a bus bar (not shown) electrically connecting two or more non-aqueous electrolyte power storage elements 1, a bus bar (not shown) electrically connecting two or more power storage units 20, and the like. good too.
  • the power storage unit 20 or the power storage device 30 may include a state monitoring device (not shown) that monitors the state of one or more non-aqueous electrolyte power storage elements.
  • a method for manufacturing the non-aqueous electrolyte storage element of the present embodiment can be appropriately selected from known methods.
  • the manufacturing method includes, for example, preparing a positive electrode having a positive electrode mixture containing elemental phosphorus, preparing a negative electrode containing lithium metal, and preparing a non-aqueous electrolyte containing compound a.
  • Preparing a positive electrode having a positive electrode mixture containing elemental phosphorus may be manufacturing a positive electrode having a positive electrode mixture containing elemental phosphorus.
  • the positive electrode can be produced, for example, by applying the positive electrode material mixture paste directly or via an intermediate layer to the positive electrode base material and drying the paste.
  • the positive electrode mixture paste contains a phosphorus element.
  • the positive electrode mixture layer further contains a positive electrode active material and optional components such as a conductive agent, a binder, a thickener, and a filler, which constitute the positive electrode mixture.
  • the form of the phosphorus element contained in the positive electrode mixture paste is preferably a phosphorus oxoacid, and among the phosphorus oxoacids, phosphonic acid is more preferable.
  • a film containing favorable phosphorus atoms is easily formed on the surface of the positive electrode.
  • formation of a uniform and favorable film derived from the compound a on the negative electrode is promoted.
  • the phosphorus oxoacid is preferably 0.1% by mass or more and 1.0% by mass or less, and 0.2% by mass or more and 0.8% by mass or less with respect to the total mass of the positive electrode mixture paste. More preferably 0.25% by mass or more and 0.6% by mass or less.
  • Preparing a negative electrode containing lithium metal may be manufacturing a negative electrode containing lithium metal.
  • the production of the negative electrode may be performed, for example, by adhering a foil-shaped negative electrode active material layer containing lithium metal to the negative electrode base material directly or via an intermediate layer.
  • Preparing the non-aqueous electrolyte containing the compound a may be preparing the non-aqueous electrolyte containing the compound a.
  • the non-aqueous electrolyte can be prepared, for example, by mixing a non-aqueous solvent, an electrolyte salt (which may contain the above compound a), and an additive (which may contain the above compound a). At least one of the electrolyte salt and the additive contains the compound a.
  • the method for manufacturing the non-aqueous electrolyte storage element includes preparing a positive electrode having the above-described positive electrode mixture containing the phosphorus element, preparing a negative electrode containing lithium metal, and preparing a non-aqueous electrolyte containing the compound a.
  • the positive electrode and the negative electrode are laminated or wound with a separator interposed between them to form an alternately stacked electrode body, the positive electrode and the negative electrode (electrode body) are housed in a container, and the container is filled with the above-mentioned non- It may comprise injecting a water electrolyte. After the injection, a non-aqueous electrolyte storage element can be obtained by sealing the injection port.
  • non-aqueous electrolyte storage device of the present invention is not limited to the above embodiments, and various modifications may be made without departing from the gist of the present invention.
  • the configuration of another embodiment can be added to the configuration of one embodiment, and part of the configuration of one embodiment can be replaced with the configuration of another embodiment or a known technique.
  • some of the configurations of certain embodiments can be deleted.
  • well-known techniques can be added to the configuration of a certain embodiment.
  • the nonaqueous electrolyte storage element is used as a chargeable/dischargeable nonaqueous electrolyte secondary battery (for example, a lithium secondary battery). etc. are optional.
  • the present invention can also be applied to capacitors such as various secondary batteries, electric double layer capacitors, and lithium ion capacitors.
  • the electrode body in which the positive electrode and the negative electrode are laminated with a separator interposed therebetween has been described, but the electrode body does not have to be provided with a separator.
  • the positive electrode and the negative electrode may be in direct contact with each other in a state in which a layer having no conductivity is formed on the positive electrode mixture layer or the negative electrode active material layer.
  • Example 1 (Preparation of positive electrode) A lithium-transition metal composite oxide having a molar ratio (Li/Me) of lithium (Li) to a transition metal (Me) of 1.33 as a positive electrode active material, wherein the transition metal (Me) is nickel (Ni) and manganese ( Mn) and a lithium transition metal composite oxide having a Ni:Mn molar ratio of 1:2 was used.
  • the positive electrode paste was applied to one side of an aluminum foil having an average thickness of 15 ⁇ m, which was a positive electrode substrate, dried, and pressed to prepare a positive electrode having a positive electrode mixture layer disposed thereon.
  • the coating amount of the positive electrode mixture layer of the prepared positive electrode was 26.5 mg/cm 2 and the porosity was 40%.
  • the produced positive electrode was made into a rectangular shape with a width of 30 mm and a length of 40 mm.
  • a lithium metal plate having a width of 31 mm, a length of 42 mm, and a thickness of 600 ⁇ m was used as the negative electrode.
  • Non-aqueous electrolyte In a non-aqueous solvent obtained by mixing FEC: TFEMC at a volume ratio of 30:70, LiPF6 is dissolved as an electrolyte salt at a concentration of 1.0 mol/dm3, and lithium difluorophosphate ( LiDFP ), which is compound a, is added as an additive. ) was added at a concentration of about 0.5% by mass with respect to the total mass of the non-aqueous electrolyte to prepare a saturated solution. The above saturated solution was obtained as a non-aqueous electrolyte.
  • LiPF6 lithium difluorophosphate ( LiDFP )
  • a polyolefin microporous film was used as a separator.
  • An electrode body was produced by laminating the positive electrode and the negative electrode with the separator interposed therebetween. This electrode body was placed in a container made of a metal-resin composite film, and after the non-aqueous electrolyte was injected therein, the container was sealed by thermal welding to obtain a non-aqueous electrolyte storage element, which is a pouch cell.
  • Example 2 and Comparative Example 1 were prepared in the same manner as in Example 1, except that the mixed amount z of phosphonic acid in the positive electrode mixture paste and the type of the additive, which is the compound a in the non-aqueous electrolyte, were changed as shown in Table 1.
  • a non-aqueous electrolyte storage device 4 was produced from the above.
  • Reference Examples 1 to 4 were prepared in the same manner as in Example 1, except that the type of negative electrode active material, the mixed amount z of phosphonic acid in the positive electrode mixture paste, and the type of additive in the non-aqueous electrolyte were changed as shown in Table 1. A nonaqueous electrolyte storage element was produced.
  • a negative electrode mixture paste containing This negative electrode mixture paste was applied to one side of a copper foil as a negative electrode base material, dried and pressed to prepare a negative electrode.
  • the negative electrode active material layer of the prepared negative electrode had a coating amount of 22 mg/cm 2 and a porosity of 35%.
  • the produced negative electrode had a rectangular shape with a width of 32 mm and a length of 42 mm.
  • the non-aqueous electrolyte storage elements of Examples 1 and 2 and Comparative Examples 1 to 4 were subjected to a charging end voltage of 4.7 V in a temperature environment of 25° C. After constant-current charging at a charging current of 0.1 C, constant-voltage charging was performed. The charging termination condition was until the charging current reached 0.05C. After a rest period of 10 minutes, a constant current discharge was performed at a discharge current of 0.1C with a final discharge voltage of 2.0V.
  • the internal resistance is a value obtained by measuring AC resistance at 1 kHz at room temperature in a discharged state. A 3560 AC milliohm high tester (manufactured by Hioki) was used as a measuring device.
  • Example 1 in which phosphonic acid was mixed in the positive electrode mixture paste and LiDFP was added to the non-aqueous electrolyte, the rate of increase in internal resistance was reduced compared to Comparative Examples 1 to 3. Moreover, the number of cycles until the occurrence of a short circuit increased.
  • Example 2 in which phosphonic acid was mixed in the positive electrode mixture paste and LiDFOB (manufactured by Sigma-Aldrich) was added to the non-aqueous electrolyte, the rate of increase in internal resistance was reduced compared to Comparative Examples 2 to 4. Moreover, the number of cycles until the occurrence of a short circuit increased.
  • LiDFOB manufactured by Sigma-Aldrich
  • the positive electrode mixture contains a phosphorus element
  • the non-aqueous electrolyte contains a compound a containing an oxygen element, a fluorine element, and at least one of the phosphorus element and the boron element
  • the non-aqueous electrolyte storage element has a high energy density, can suppress an increase in internal resistance due to charge-discharge cycles, and can delay the occurrence of an internal short circuit. rice field.
  • the present invention can be applied to electronic devices such as personal computers, communication terminals, non-aqueous electrolyte storage elements and storage devices used as power sources for automobiles and the like.
  • Non-aqueous electrolyte storage element 1 Non-aqueous electrolyte storage element 2 Electrode body 3 Container 4 Positive electrode terminal 41 Positive electrode lead 5 Negative electrode terminal 51 Negative electrode lead 20 Storage unit 30 Storage device

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Abstract

A nonaqueous electrolyte power storage element according to one aspect of the present invention is provided with a positive electrode that comprises a positive electrode mixture containing elemental phosphorus, a negative electrode that contains lithium metal, and a nonaqueous electrolyte that contains a compound a; and the compound a contains elemental fluorine, and at least one of elemental phosphorus and elemental boron.

Description

非水電解質蓄電素子、及び蓄電装置NON-AQUEOUS ELECTROLYTE STORAGE ELEMENT AND POWER STORAGE DEVICE
　本発明は、非水電解質蓄電素子、及び蓄電装置に関する。 The present invention relates to non-aqueous electrolyte power storage elements and power storage devices.
　リチウムイオン二次電池に代表される非水電解質二次電池は、エネルギー密度の高さから、パーソナルコンピュータ、通信端末等の電子機器、自動車等に多用されている。上記非水電解質二次電池は、一般的には、セパレータで電気的に隔離された一対の電極と、この電極間に介在する非水電解質とを有し、両電極間でイオンの受け渡しを行うことで充放電するよう構成される。また、非水電解質二次電池以外の非水電解質蓄電素子として、リチウムイオンキャパシタや電気二重層キャパシタ等のキャパシタも広く普及している。 Non-aqueous electrolyte secondary batteries, typified by lithium-ion secondary batteries, are widely used in electronic devices such as personal computers, communication terminals, and automobiles due to their high energy density. The non-aqueous electrolyte secondary battery generally has a pair of electrodes electrically isolated by a separator and a non-aqueous electrolyte interposed between the electrodes, and transfers ions between the electrodes. It is configured to be charged and discharged by Capacitors such as lithium ion capacitors and electric double layer capacitors are also widely used as non-aqueous electrolyte storage elements other than non-aqueous electrolyte secondary batteries.
　非水電解質蓄電素子の一例として、特許文献１には、負極にリチウム金属箔を用いたリチウム二次電池が開示されている。 As an example of a non-aqueous electrolyte storage element, Patent Document 1 discloses a lithium secondary battery using a lithium metal foil as a negative electrode.
再表２０１７－０４７０１９号公報Retable 2017-047019
　しかしながら、上記特許文献に示す負極にリチウム金属を用いるリチウム二次電池は、エネルギー密度が高い一方で、充放電サイクルに伴って、内部抵抗が増加するおそれがあり、かつ充電の際に負極表面でリチウム金属が樹枝状に析出することがあり（以下、樹枝状の形態をしたリチウム金属を「デンドライト」という。）、このデンドライト析出による内部短絡が発生するおそれがある。 However, the lithium secondary battery using lithium metal for the negative electrode disclosed in the above patent document has a high energy density, but there is a risk that the internal resistance will increase with charge-discharge cycles, and the surface of the negative electrode during charging. Lithium metal may be deposited in a dendritic form (hereinafter, lithium metal in a dendritic form is referred to as "dendrite"), and this dendrite deposition may cause an internal short circuit.
　本発明の目的は、エネルギー密度が高く、充放電サイクルに伴う内部抵抗の増加を抑制することができ、かつ内部短絡の発生を遅延させることが可能な非水電解質蓄電素子、及び蓄電装置を提供することである。 An object of the present invention is to provide a non-aqueous electrolyte storage element and a storage device that have high energy density, can suppress an increase in internal resistance due to charge/discharge cycles, and can delay the occurrence of an internal short circuit. It is to be.
　本発明の一側面に係る非水電解質蓄電素子は、リン元素を含む正極合剤を有する正極と、リチウム金属を含む負極と、化合物ａを含む非水電解質とを備え、上記化合物ａが酸素元素と、フッ素元素と、リン元素及びホウ素元素のうち少なくとも一方とを含む。 A non-aqueous electrolyte storage element according to one aspect of the present invention includes a positive electrode having a positive electrode mixture containing a phosphorus element, a negative electrode containing lithium metal, and a non-aqueous electrolyte containing a compound a, wherein the compound a is an oxygen element. , elemental fluorine, and at least one of elemental phosphorus and elemental boron.
　本発明の他の一態様は、非水電解質蓄電素子を二以上備え、且つ上記本発明の他の一態様に係る非水電解質蓄電素子を一以上備えた蓄電装置である。 Another aspect of the present invention is a power storage device including two or more non-aqueous electrolyte storage elements and one or more non-aqueous electrolyte storage elements according to another aspect of the present invention.
　本発明の一側面に係る非水電解質蓄電素子及び蓄電装置は、エネルギー密度が高く、充放電サイクルに伴う内部抵抗の増加を抑制することができ、かつ内部短絡の発生を遅延させることが可能である。 The non-aqueous electrolyte power storage element and the power storage device according to one aspect of the present invention have high energy density, can suppress an increase in internal resistance due to charge-discharge cycles, and can delay the occurrence of an internal short circuit. be.
図１は、非水電解質蓄電素子の一実施形態を示す透視斜視図である。FIG. 1 is a see-through perspective view showing one embodiment of a non-aqueous electrolyte storage element. 図２は、非水電解質蓄電素子を複数個集合して構成した蓄電装置の一実施形態を示す概略図である。FIG. 2 is a schematic diagram showing an embodiment of a power storage device configured by assembling a plurality of non-aqueous electrolyte power storage elements.
　初めに、本明細書によって開示される非水電解質蓄電素子及び蓄電装置の概要について説明する。 First, an outline of the non-aqueous electrolyte power storage element and power storage device disclosed by the present specification will be described.
　本発明の一側面に係る非水電解質蓄電素子は、リン元素を含む正極合剤を有する正極と、リチウム金属を含む負極と、化合物ａを含む非水電解質とを備え、上記化合物ａが酸素元素と、フッ素元素と、リン元素及びホウ素元素のうち少なくとも一方とを含む。 A non-aqueous electrolyte storage element according to one aspect of the present invention includes a positive electrode having a positive electrode mixture containing a phosphorus element, a negative electrode containing lithium metal, and a non-aqueous electrolyte containing a compound a, wherein the compound a is an oxygen element. , elemental fluorine, and at least one of elemental phosphorus and elemental boron.
　当該非水電解質蓄電素子は、エネルギー密度が高く、充放電サイクルに伴う内部抵抗の増加を抑制することができ、かつ内部短絡の発生を遅延させることが可能である。この理由としては、以下の内容が推測される。当該非水電解質蓄電素子は、リチウム金属を含む負極を備えるため、エネルギー密度が高い。リチウム金属を含む負極を備える従来の非水電解質蓄電素子においては、負極表面で非水電解質の分解が著しく促進されるため、非水電解質のイオン伝導性が大きく低下する。さらに、上記分解により負極表面に形成される被膜が厚さを増しやすく、負極表面のイオン伝導性が低下する。その結果、内部抵抗が増加しやすい。また、上記被膜が不均一に形成され、負極で局所的な電流集中が発生することにより、充電の際に負極表面でリチウム金属のデンドライト析出が進行しやすく、その結果、内部短絡が起こりやすい。これに対し、当該非水電解質蓄電素子においては、非水電解質に含まれる上記化合物ａが非水電解質の他の成分に優先して負極のリチウム金属と反応し、負極表面に上記化合物ａに由来する被膜を形成する。負極における上記化合物ａに由来する被膜は、非水電解質の他の成分の分解を抑制することができる。また、上記化合物ａに由来する被膜は、上述の組成を有する上記化合物ａに由来するため、比較的高いイオン伝導性を有する。さらに、上記化合物ａに由来する被膜は均一に形成されやすく、負極における局所的な電流集中を抑制することができる。一方、当該非水電解質蓄電素子の正極はリン元素を含む正極合剤を有するため、この正極では正極合剤と非水電解質との反応により上記リン元素由来の被膜が形成される。正極における上記リン元素由来の被膜は、正極表面での非水電解質の分解を抑制しつつ、非水電解質に含まれる上記化合物ａが負極表面で選択的に反応するよう寄与する。このため正極における上記リン由来の被膜の存在により、負極における上記化合物ａに由来する被膜がさらに均一かつ良好に形成されやすい。上述の理由から、当該非水電解質蓄電素子においては、リチウム金属を含む負極が高い反応性を示すにもかかわらず、正極合剤に含まれるリン元素と非水電解質に含まれる化合物ａとの作用により、正負両極に良好な被膜が形成され、その結果、内部抵抗の増加及び内部短絡の原因となるデンドライト析出が効果的に軽減されるものと考えられる。 The non-aqueous electrolyte storage element has a high energy density, can suppress an increase in internal resistance due to charge-discharge cycles, and can delay the occurrence of an internal short circuit. The reason for this is presumed to be as follows. Since the non-aqueous electrolyte storage element includes a negative electrode containing lithium metal, the energy density is high. In a conventional non-aqueous electrolyte storage element having a negative electrode containing lithium metal, the decomposition of the non-aqueous electrolyte is significantly accelerated on the surface of the negative electrode, so that the ionic conductivity of the non-aqueous electrolyte is greatly reduced. Furthermore, the decomposition tends to increase the thickness of the film formed on the surface of the negative electrode, and the ionic conductivity of the surface of the negative electrode decreases. As a result, the internal resistance tends to increase. In addition, the film is unevenly formed, causing localized current concentration at the negative electrode, which facilitates dendrite deposition of lithium metal on the surface of the negative electrode during charging, and as a result, tends to cause an internal short circuit. On the other hand, in the non-aqueous electrolyte storage element, the compound a contained in the non-aqueous electrolyte reacts with the lithium metal of the negative electrode preferentially over other components of the non-aqueous electrolyte, and the negative electrode surface is derived from the compound a. form a coating that The coating film derived from compound a in the negative electrode can suppress decomposition of other components of the non-aqueous electrolyte. In addition, the film derived from compound a has relatively high ionic conductivity because it is derived from compound a having the composition described above. Furthermore, the film derived from the compound a is easily formed uniformly, and local current concentration in the negative electrode can be suppressed. On the other hand, since the positive electrode of the non-aqueous electrolyte storage element has a positive electrode mixture containing phosphorus element, the positive electrode film is formed from the phosphorus element by the reaction between the positive electrode mixture and the non-aqueous electrolyte. The phosphorus element-derived film on the positive electrode suppresses the decomposition of the non-aqueous electrolyte on the positive electrode surface and contributes to the selective reaction of the compound a contained in the non-aqueous electrolyte on the negative electrode surface. Therefore, the presence of the film derived from phosphorus on the positive electrode facilitates the formation of the film derived from the compound a on the negative electrode more uniformly and satisfactorily. For the reasons described above, in the non-aqueous electrolyte storage element, although the negative electrode containing lithium metal exhibits high reactivity, the action of the phosphorus element contained in the positive electrode mixture and the compound a contained in the non-aqueous electrolyte It is thought that good coatings are formed on both the positive and negative electrodes, and as a result, dendrite precipitation, which causes an increase in internal resistance and an internal short circuit, is effectively reduced.
　ここで、上記化合物ａは、ジフルオロリン酸リチウム（ＬｉＤＦＰ）又はリチウムジフルオロオキサレートボレート（ＬｉＤＦＯＢ）であってもよい。このように上記化合物ａがジフルオロリン酸リチウム（ＬｉＤＦＰ）又はリチウムジフルオロオキサレートボレート（ＬｉＤＦＯＢ）であれば、負極における上記化合物ａに由来する被膜がさらに均一かつ良好に形成されやすい。 Here, the compound a may be lithium difluorophosphate (LiDFP) or lithium difluorooxalate borate (LiDFOB). As described above, when the compound a is lithium difluorophosphate (LiDFP) or lithium difluorooxalate borate (LiDFOB), the film derived from the compound a on the negative electrode is likely to be formed more uniformly and satisfactorily.
　ここで、エックス線光電子分光法による上記正極合剤のスペクトルにおいて、Ｐ２ｐのピーク位置が１３５ｅＶ以下であってもよい。上記スペクトルにおいて１３５ｅＶ以下に現れるＰ２ｐのピークは、ホスホン酸等のリンのオキソ酸に由来するリン原子のピークである。すなわち、正極合剤表面にリンのオキソ酸に由来するリン原子が存在し、正極表面に上記リン原子を含む被膜が形成されていることを示している。このように正極表面に上記リン原子を含む被膜が形成される場合には、正極表面での非水電解質の分解がさらに抑制される。また、正極における上記リン原子を含む被膜の形成により、上記化合物ａが正極表面よりも負極表面でより選択的に反応しやすくなるため、負極における上記化合物ａに由来する被膜がさらに均一かつ良好に形成されやすい。 Here, in the spectrum of the positive electrode mixture obtained by X-ray photoelectron spectroscopy, the peak position of P2p may be 135 eV or less. The P2p peak appearing below 135 eV in the above spectrum is the peak of a phosphorus atom derived from a phosphorus oxoacid such as phosphonic acid. That is, it indicates that phosphorus atoms derived from the oxoacid of phosphorus are present on the surface of the positive electrode mixture, and that a film containing the phosphorus atoms is formed on the surface of the positive electrode. When the film containing the phosphorus atoms is formed on the surface of the positive electrode in this way, the decomposition of the non-aqueous electrolyte on the surface of the positive electrode is further suppressed. In addition, the formation of the film containing the phosphorus atom on the positive electrode makes it easier for the compound a to react more selectively on the surface of the negative electrode than on the surface of the positive electrode, so that the film derived from the compound a on the negative electrode is more uniform and good. easy to form.
　なお、エックス線光電子分光法（ＸＰＳ）による正極合剤のスペクトルの測定に用いる試料は、次の方法により準備する。非水電解質蓄電素子を、０．１Ｃの電流で、通常使用時の放電終止電圧まで放電し、放電状態とする。ここで、「通常使用時」とは、当該非水電解質蓄電素子において推奨され、又は指定される放電条件を採用して当該非水電解質蓄電素子を使用する場合をいう。放電状態の非水電解質蓄電素子を解体して正極を取り出し、ジメチルカーボネートを用いて正極を充分に洗浄した後、室温にて減圧乾燥を行う。乾燥後の正極を、所定サイズ（例えば２×２ｃｍ２）に切り出し、ＸＰＳによるスペクトル測定における試料とする。非水電解質蓄電素子の解体からＸＰＳによるスペクトル測定における試料の作製までの作業は、露点－６０℃以下のアルゴン雰囲気中で行い、試料はトランスファーベッセルに封入して大気非暴露にてＸＰＳによるスペクトルの測定に供する。正極合剤のＸＰＳによるスペクトル測定における使用装置及び測定条件は以下のとおりである。
装置：ＫＲＡＴＯＳ　　ＡＮＡＬＹＴＩＣＡＬ社の「ＡＸＩＳ　　ＮＯＶＡ」
Ｘ線源：単色化ＡｌＫα
管電圧：１５ｋＶ
管電流：１０ｍＡ
中和銃：ＯＮ
分析面積：７００μｍ×３００μｍ
測定範囲：Ｐ２ｐ＝１４２から１２５ｅＶ、Ｃ１ｓ＝３００から２７２ｅＶ
測定間隔：０．１ｅＶ
Ｄｗｅｌｌ　Ｔｉｍｅ：Ｐ２ｐ＝４２６ミリ秒、Ｃ１ｓ＝２５０ミリ秒
積算回数：Ｐ２ｐ＝１５回、Ｃ１ｓ＝８回 A sample used for measuring the spectrum of the positive electrode mixture by X-ray photoelectron spectroscopy (XPS) is prepared by the following method. The non-aqueous electrolyte storage element is discharged with a current of 0.1 C to the final discharge voltage in normal use, and is placed in a discharged state. Here, "during normal use" refers to the case where the non-aqueous electrolyte storage element is used under discharge conditions recommended or specified for the non-aqueous electrolyte storage element. The discharged non-aqueous electrolyte storage element is disassembled, the positive electrode is taken out, the positive electrode is thoroughly washed with dimethyl carbonate, and then dried under reduced pressure at room temperature. The dried positive electrode is cut into a predetermined size (for example, 2×2 cm 2 ) and used as a sample for spectrum measurement by XPS. The work from the dismantling of the non-aqueous electrolyte storage element to the preparation of the sample for spectral measurement by XPS was performed in an argon atmosphere with a dew point of -60°C or less, and the sample was enclosed in a transfer vessel and was not exposed to the atmosphere. Provide for measurement. The equipment used and the measurement conditions in XPS spectrum measurement of the positive electrode mixture are as follows.
Apparatus: KRATOS ANALYTICAL "AXIS NOVA"
X-ray source: monochromatic AlKα
Tube voltage: 15kV
Tube current: 10mA
Neutralization gun: ON
Analysis area: 700 μm × 300 μm
Measurement range: P2p = 142 to 125 eV, C1s = 300 to 272 eV
Measurement interval: 0.1 eV
Dwell Time: P2p = 426 milliseconds, C1s = 250 milliseconds Integration count: P2p = 15 times, C1s = 8 times
　また、上記スペクトルにおけるＰ２ｐのピーク位置は、次のようにして求められる値とする。まず、Ｃ１ｓにおけるｓｐ２炭素のピークの結合エネルギーを２８４．８ｅＶとし、得られたすべてのスペクトルを補正する。次に、それぞれのスペクトルに対して、直線法を用いてバックグラウンドを除去することにより、水平化処理を行う。水平化処理後のスペクトルの１３０から１３８ｅＶの範囲において、ピーク強度が最も高い値を示す結合エネルギーをＰ２ｐのピーク位置とする。 Also, the P2p peak position in the above spectrum is a value obtained as follows. First, the binding energy of the sp2 carbon peak in C1s is set to 284.8 eV, and all spectra obtained are corrected. Each spectrum is then smoothed by subtracting the background using the linear method. The binding energy showing the highest peak intensity in the range of 130 to 138 eV in the spectrum after flattening is defined as the P2p peak position.
　本発明の一実施形態に係る非水電解質蓄電素子の構成、蓄電装置の構成、及び非水電解質蓄電素子の製造方法、並びにその他の実施形態について詳述する。なお、各実施形態に用いられる各構成部材（各構成要素）の名称は、背景技術に用いられる各構成部材（各構成要素）の名称と異なる場合がある。 The configuration of the non-aqueous electrolyte storage element, the configuration of the storage device, the method for manufacturing the non-aqueous electrolyte storage element, and other embodiments according to one embodiment of the present invention will be described in detail. Note that the name of each component (each component) used in each embodiment may be different from the name of each component (each component) used in the background art.
＜非水電解質蓄電素子の構成＞
　本発明の一実施形態に係る非水電解質蓄電素子（以下、単に「蓄電素子」ともいう。）は、正極、負極及びセパレータを有する電極体と、非水電解質と、上記電極体及び非水電解質を収容する容器と、を備える。電極体は、通常、複数の正極及び複数の負極がセパレータを介して積層された積層型、又は、正極及び負極がセパレータを介して積層された状態で巻回された巻回型である。非水電解質は、正極、負極及びセパレータに含まれた状態で存在する。非水電解質蓄電素子の一例として、非水電解質二次電池（以下、単に「二次電池」ともいう。）について説明する。 <Structure of non-aqueous electrolyte storage element>
A non-aqueous electrolyte storage element according to one embodiment of the present invention (hereinafter also simply referred to as "storage element") includes an electrode body having a positive electrode, a negative electrode and a separator, a non-aqueous electrolyte, the electrode body and the non-aqueous electrolyte and a container that houses the The electrode body is usually a laminated type in which a plurality of positive electrodes and a plurality of negative electrodes are laminated with separators interposed therebetween, or a wound type in which positive electrodes and negative electrodes are laminated with separators interposed and wound. The non-aqueous electrolyte exists in a state contained in the positive electrode, the negative electrode and the separator. As an example of the non-aqueous electrolyte storage element, a non-aqueous electrolyte secondary battery (hereinafter also simply referred to as "secondary battery") will be described.
［正極］
　上記正極は、正極基材と、この正極基材に直接又は中間層を介して配される正極合剤層とを有する。 [Positive electrode]
The positive electrode has a positive electrode base material and a positive electrode material mixture layer disposed on the positive electrode base material directly or via an intermediate layer.
（正極基材）
　正極基材は、導電性を有する。「導電性」を有するか否かは、ＪＩＳ－Ｈ－０５０５（１９７５年）に準拠して測定される体積抵抗率が１０７Ω・ｃｍを閾値として判定する。正極基材の材質としては、アルミニウム、チタン、タンタル、ステンレス鋼等の金属又はこれらの合金が用いられる。これらの中でも、耐電位性、導電性の高さ、及びコストの観点からアルミニウム又はアルミニウム合金が好ましい。正極基材としては、箔、蒸着膜、メッシュ、多孔質材料等が挙げられ、コストの観点から箔が好ましい。したがって、正極基材としてはアルミニウム箔又はアルミニウム合金箔が好ましい。アルミニウム又はアルミニウム合金としては、ＪＩＳ－Ｈ－４０００（２０１４年）又はＪＩＳ－Ｈ４１６０（２００６年）に規定されるＡ１０８５、Ａ３００３、Ａ１Ｎ３０等が例示できる。 (Positive electrode base material)
A positive electrode base material has electroconductivity. Whether or not a material has "conductivity" is determined using a volume resistivity of 10 7 Ω·cm as a threshold measured according to JIS-H-0505 (1975). As the material for the positive electrode substrate, metals such as aluminum, titanium, tantalum and stainless steel, or alloys thereof are used. Among these, aluminum or an aluminum alloy is preferable from the viewpoint of potential resistance, high conductivity, and cost. Examples of the positive electrode substrate include foil, deposited film, mesh, porous material, and the like, and foil is preferable from the viewpoint of cost. Therefore, aluminum foil or aluminum alloy foil is preferable as the positive electrode substrate. Examples of aluminum or aluminum alloys include A1085, A3003, A1N30, etc. defined in JIS-H-4000 (2014) or JIS-H4160 (2006).
　正極基材の平均厚さは、３μｍ以上５０μｍ以下が好ましく、５μｍ以上４０μｍ以下がより好ましく、８μｍ以上３０μｍ以下がさらに好ましく、１０μｍ以上２５μｍ以下が特に好ましい。正極基材の平均厚さを上記の範囲とすることで、正極基材の強度を高めつつ、二次電池の体積当たりのエネルギー密度を高めることができる。 The average thickness of the positive electrode substrate is preferably 3 µm or more and 50 µm or less, more preferably 5 µm or more and 40 µm or less, even more preferably 8 µm or more and 30 µm or less, and particularly preferably 10 µm or more and 25 µm or less. By setting the average thickness of the positive electrode substrate within the above range, the energy density per volume of the secondary battery can be increased while increasing the strength of the positive electrode substrate.
（中間層）
　中間層は、正極基材と正極合剤層との間に配される層である。中間層は、炭素粒子等の導電剤を含むことで正極基材と正極合剤層との接触抵抗を低減する。中間層の構成は特に限定されず、例えば、バインダ及び導電剤を含む。 (middle layer)
The intermediate layer is a layer arranged between the positive electrode substrate and the positive electrode material mixture layer. The intermediate layer contains a conductive agent such as carbon particles to reduce the contact resistance between the positive electrode substrate and the positive electrode mixture layer. The composition of the intermediate layer is not particularly limited, and includes, for example, a binder and a conductive agent.
（正極合剤層）
　正極合剤層は、正極合剤によって形成される層である。この正極合剤は、リン元素を含む。上記正極合剤は、さらに正極活物質を含み、その他必要に応じて導電剤、バインダ（結着剤）、増粘剤、フィラー等の任意成分を含む。正極合剤層は、通常、正極合剤ペーストの塗工及び乾燥により正極基材表面に形成される。 (Positive electrode mixture layer)
The positive electrode mixture layer is a layer formed of a positive electrode mixture. This positive electrode mixture contains a phosphorus element. The positive electrode mixture further contains a positive electrode active material, and optionally other optional components such as a conductive agent, a binder (binder), a thickener, and a filler. The positive electrode material mixture layer is usually formed on the surface of the positive electrode substrate by coating and drying a positive electrode material mixture paste.
　正極活物質としては、公知の正極活物質の中から適宜選択できる。リチウム二次電池用の正極活物質としては、例えば、α－ＮａＦｅＯ２型結晶構造を有するリチウム遷移金属複合酸化物、スピネル型結晶構造を有するリチウム遷移金属複合酸化物、ポリアニオン化合物、カルコゲン化合物、硫黄等が挙げられる。α－ＮａＦｅＯ２型結晶構造を有するリチウム遷移金属複合酸化物として、例えば、Ｌｉ［ＬｉｘＮｉ（１－ｘ）］Ｏ２（０≦ｘ＜０．５）、Ｌｉ［ＬｉｘＮｉγＣｏ（１－ｘ－γ）］Ｏ２（０≦ｘ＜０．５、０＜γ＜１）、Ｌｉ［ＬｉｘＣｏ（１－ｘ）］Ｏ２（０≦ｘ＜０．５）、Ｌｉ［ＬｉｘＮｉγＭｎ（１－ｘ－γ）］Ｏ２（０≦ｘ＜０．５、０＜γ＜１）、Ｌｉ［ＬｉｘＮｉγＭｎβＣｏ（１－ｘ－γ－β）］Ｏ２（０≦ｘ＜０．５、０＜γ、０＜β、０．５＜γ＋β＜１）、Ｌｉ［ＬｉｘＮｉγＣｏβＡｌ（１－ｘ－γ－β）］Ｏ２（０≦ｘ＜０．５、０＜γ、０＜β、０．５＜γ＋β＜１）等が挙げられる。スピネル型結晶構造を有するリチウム遷移金属複合酸化物として、ＬｉｘＭｎ２Ｏ４、ＬｉｘＮｉγＭｎ（２－γ）Ｏ４等が挙げられる。ポリアニオン化合物として、ＬｉＦｅＰＯ４、ＬｉＭｎＰＯ４、ＬｉＮｉＰＯ４、ＬｉＣｏＰＯ４，Ｌｉ３Ｖ２（ＰＯ４）３、Ｌｉ２ＭｎＳｉＯ４、Ｌｉ２ＣｏＰＯ４Ｆ等が挙げられる。カルコゲン化合物として、二硫化チタン、二硫化モリブデン、二酸化モリブデン等が挙げられる。これらの材料中の原子又はポリアニオンは、他の元素からなる原子又はアニオン種で一部が置換されていてもよい。これらの材料は表面が他の材料で被覆されていてもよい。正極合剤層においては、これら材料の１種を単独で用いてもよく、２種以上を混合して用いてもよい。 The positive electrode active material can be appropriately selected from known positive electrode active materials. Examples of positive electrode active materials for lithium secondary batteries include lithium transition metal composite oxides having a α-NaFeO 2 type crystal structure, lithium transition metal composite oxides having a spinel crystal structure, polyanion compounds, chalcogen compounds, sulfur etc. Examples of lithium transition metal composite oxides having an α-NaFeO 2 type crystal structure include Li[Li x Ni (1-x) ]O 2 (0≦x<0.5), Li[Li x Ni γ Co ( 1-x-γ) ]O 2 (0≦x<0.5, 0<γ<1), Li[Li x Co (1-x) ]O 2 (0≦x<0.5), Li[ Li x Ni γ Mn (1-x-γ) ]O 2 (0≦x<0.5, 0<γ<1), Li[Li x Ni γ Mn β Co (1-x-γ-β) ] O 2 (0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1), Li[Li x Ni γ Co β Al (1-x-γ-β) ]O 2 ( 0≦x<0.5, 0<γ, 0<β, 0.5<γ+β<1) and the like. Examples of lithium transition metal composite oxides having a spinel crystal structure include Li x Mn 2 O 4 and Li x Ni γ Mn (2-γ) O 4 . Examples of polyanion compounds include LiFePO4 , LiMnPO4 , LiNiPO4 , LiCoPO4, Li3V2(PO4)3 , Li2MnSiO4 , Li2CoPO4F and the like. Examples of chalcogen compounds include titanium disulfide, molybdenum disulfide, and molybdenum dioxide. The atoms or polyanions in these materials may be partially substituted with atoms or anionic species of other elements. These materials may be coated with other materials on their surfaces. In the positive electrode mixture layer, one kind of these materials may be used alone, or two or more kinds may be mixed and used.
　正極活物質は、通常、粒子（粉体）である。正極活物質の平均粒径は、例えば、０．１μｍ以上２０μｍ以下とすることが好ましい。正極活物質の平均粒径を上記下限以上とすることで、正極活物質の製造又は取り扱いが容易になる。正極活物質の平均粒径を上記上限以下とすることで、正極合剤層の電子伝導性が向上する。なお、正極活物質と他の材料との複合体を用いる場合、該複合体の平均粒径を正極活物質の平均粒径とする。「平均粒径」とは、ＪＩＳ－Ｚ－８８２５（２０１３年）に準拠し、粒子を溶媒で希釈した希釈液に対しレーザ回折・散乱法により測定した粒径分布に基づき、ＪＩＳ－Ｚ－８８１９－２（２００１年）に準拠し計算される体積基準積算分布が５０％となる値を意味する。 The positive electrode active material is usually particles (powder). The average particle size of the positive electrode active material is preferably, for example, 0.1 μm or more and 20 μm or less. By making the average particle diameter of the positive electrode active material equal to or more than the above lower limit, the production or handling of the positive electrode active material becomes easy. By making the average particle size of the positive electrode active material equal to or less than the above upper limit, the electron conductivity of the positive electrode mixture layer is improved. Note that when a composite of a positive electrode active material and another material is used, the average particle size of the composite is taken as the average particle size of the positive electrode active material. "Average particle size" is based on JIS-Z-8825 (2013), based on the particle size distribution measured by a laser diffraction / scattering method for a diluted solution in which particles are diluted with a solvent, JIS-Z-8819 -2 (2001) means a value at which the volume-based integrated distribution calculated according to 50%.
　粉体を所定の粒径で得るためには粉砕機や分級機等が用いられる。粉砕方法として、例えば、乳鉢、ボールミル、サンドミル、振動ボールミル、遊星ボールミル、ジェットミル、カウンタージェットミル、旋回気流型ジェットミル又は篩等を用いる方法が挙げられる。粉砕時には水、あるいはヘキサン等の有機溶剤を共存させた湿式粉砕を用いることもできる。分級方法としては、篩や風力分級機等が、乾式、湿式ともに必要に応じて用いられる。 Pulverizers, classifiers, etc. are used to obtain powder with a predetermined particle size. Pulverization methods include, for example, methods using a mortar, ball mill, sand mill, vibrating ball mill, planetary ball mill, jet mill, counter jet mill, whirling jet mill, or sieve. At the time of pulverization, wet pulverization in which water or an organic solvent such as hexane is allowed to coexist can also be used. As a classification method, a sieve, an air classifier, or the like is used as necessary, both dry and wet.
　正極合剤層における正極活物質の含有量は、５０質量％以上９９質量％以下が好ましく、７０質量％以上９８質量％以下がより好ましく、８０質量％以上９５質量％以下がさらに好ましい。正極活物質の含有量を上記の範囲とすることで、正極合剤層の高エネルギー密度化と製造性を両立できる。 The content of the positive electrode active material in the positive electrode mixture layer is preferably 50% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 98% by mass or less, and even more preferably 80% by mass or more and 95% by mass or less. By setting the content of the positive electrode active material within the above range, it is possible to achieve both high energy density of the positive electrode mixture layer and manufacturability.
　正極合剤に含まれる上記リン元素は、リンのオキソ酸又は上記リンのオキソ酸から得られる誘導体の形態で正極合剤中に存在していることが好ましい。すなわち、正極合剤がリンのオキソ酸又はその誘導体を含むことが好ましい。上記リンのオキソ酸とは、リン原子にヒドロキシ基（－ＯＨ）とオキシ基（＝Ｏ）とが結合した構造を有する化合物を指す。上記リンのオキソ酸としては、リン酸（Ｈ３ＰＯ４）、ホスホン酸（Ｈ３ＰＯ３）、ホスフィン酸（Ｈ３ＰＯ２）、ピロリン酸（Ｈ４Ｐ２Ｏ７）、ポリリン酸等が挙げられ、これらの中でもホスホン酸がより好ましい。上記リンのオキソ酸から得られる誘導体としては、リンのオキソ酸塩及びリンのオキソ酸エステル等が挙げられる。このように、正極合剤がリンのオキソ酸又はその誘導体を含むことにより、正極表面に良好なリン原子を含む被膜が形成されやすい。また、正極表面に上記リン原子を含む被膜が形成されることにより、負極における均一かつ良好な化合物ａに由来する被膜形成が促進される。 The elemental phosphorus contained in the positive electrode mixture is preferably present in the positive electrode mixture in the form of a phosphorus oxoacid or a derivative obtained from the phosphorus oxoacid. That is, the positive electrode mixture preferably contains a phosphorus oxoacid or a derivative thereof. The phosphorus oxoacid refers to a compound having a structure in which a hydroxyl group (--OH) and an oxy group (=O) are bonded to a phosphorus atom. Examples of the phosphorus oxoacid include phosphoric acid (H 3 PO 4 ), phosphonic acid (H 3 PO 3 ), phosphinic acid (H 3 PO 2 ), pyrophosphoric acid (H 4 P 2 O 7 ), polyphosphoric acid, and the like. Among these, phosphonic acid is more preferable. Derivatives obtained from the above phosphorus oxoacids include phosphorus oxoacid salts and phosphorus oxoacid esters. In this way, when the positive electrode mixture contains the oxoacid of phosphorus or a derivative thereof, a favorable film containing phosphorus atoms is easily formed on the surface of the positive electrode. In addition, the formation of the film containing the phosphorus atoms on the surface of the positive electrode promotes uniform and favorable film formation derived from the compound a on the negative electrode.
　上記エックス線光電子分光法による上記正極合剤層（上記正極合剤）のスペクトルにおいて、Ｐ２ｐのピーク位置は１３５ｅＶ以下が好ましい。また、このピーク位置は１３１ｅＶ以上が好ましく、１３２ｅＶ以上がより好ましく、１３３ｅＶ以上がさらに好ましい。 In the spectrum of the positive electrode mixture layer (positive electrode mixture) obtained by the X-ray photoelectron spectroscopy, the peak position of P2p is preferably 135 eV or less. The peak position is preferably 131 eV or higher, more preferably 132 eV or higher, and even more preferably 133 eV or higher.
　上記範囲に現れるＰ２ｐのピークは、ホスホン酸等のリンのオキソ酸に由来するリン原子のピークである。すなわち、上記Ｐ２ｐのピークは、正極合剤表面にリンのオキソ酸に由来するリン原子が存在し、上記リン原子は正極表面で被膜を形成していることを示している。このように正極表面に上記リン原子を含む被膜が形成されることにより、正極表面での非水電解質の分解がさらに抑制される。また、このような被膜の形成により、負極における均一かつ良好な被膜形成が促進される。なお、上記スペクトルにおいて、上記範囲外のＰ２ｐのピークが存在してもよい。結合エネルギーが１３５ｅＶ以上の範囲に表れるＰ２ｐのピークは、例えばリンのフッ化物に由来するリン原子のピークである。 The P2p peaks appearing in the above range are peaks of phosphorus atoms derived from phosphorus oxoacids such as phosphonic acid. That is, the P2p peak indicates that phosphorus atoms derived from the oxoacid of phosphorus exist on the surface of the positive electrode mixture, and the phosphorus atoms form a film on the surface of the positive electrode. By forming the film containing the phosphorus atoms on the surface of the positive electrode in this way, decomposition of the non-aqueous electrolyte on the surface of the positive electrode is further suppressed. In addition, the formation of such a coating promotes uniform and good coating formation on the negative electrode. In addition, in the above spectrum, a P2p peak outside the above range may be present. The P2p peak appearing in the range of binding energy of 135 eV or more is the peak of phosphorus atoms derived from, for example, fluoride of phosphorus.
　導電剤は、導電性を有する材料であれば特に限定されない。このような導電剤としては、例えば、炭素質材料、金属、導電性セラミックス等が挙げられる。炭素質材料としては、黒鉛、非黒鉛質炭素、グラフェン系炭素等が挙げられる。非黒鉛質炭素としては、カーボンナノファイバー、ピッチ系炭素繊維、カーボンブラック等が挙げられる。カーボンブラックとしては、ファーネスブラック、アセチレンブラック、ケッチェンブラック等が挙げられる。グラフェン系炭素としては、グラフェン、カーボンナノチューブ（ＣＮＴ）、フラーレン等が挙げられる。導電剤の形状としては、粉状、繊維状等が挙げられる。導電剤としては、これらの材料の１種を単独で用いてもよく、２種以上を混合して用いてもよい。また、これらの材料を複合化して用いてもよい。例えば、カーボンブラックとＣＮＴとを複合化した材料を用いてもよい。これらの中でも、電子伝導性及び塗工性の観点よりカーボンブラックが好ましく、中でもアセチレンブラックが好ましい。 The conductive agent is not particularly limited as long as it is a conductive material. Examples of such conductive agents include carbonaceous materials, metals, and conductive ceramics. Carbonaceous materials include graphite, non-graphitic carbon, graphene-based carbon, and the like. Examples of non-graphitic carbon include carbon nanofiber, pitch-based carbon fiber, and carbon black. Examples of carbon black include furnace black, acetylene black, and ketjen black. Graphene-based carbon includes graphene, carbon nanotube (CNT), fullerene, and the like. The shape of the conductive agent may be powdery, fibrous, or the like. As the conductive agent, one type of these materials may be used alone, or two or more types may be mixed and used. Also, these materials may be combined for use. For example, a composite material of carbon black and CNT may be used. Among these, carbon black is preferable from the viewpoint of electron conductivity and coatability, and acetylene black is particularly preferable.
　正極合剤層における導電剤の含有量は、１質量％以上１０質量％以下が好ましく、３質量％以上９質量％以下がより好ましい。導電剤の含有量を上記の範囲とすることで、二次電池のエネルギー密度を高めることができる。 The content of the conductive agent in the positive electrode mixture layer is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less. By setting the content of the conductive agent within the above range, the energy density of the secondary battery can be increased.
　バインダとしては、例えば、フッ素樹脂（ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶＤＦ）等）、ポリエチレン、ポリプロピレン、ポリアクリル、ポリイミド等の熱可塑性樹脂；エチレン－プロピレン－ジエンゴム（ＥＰＤＭ）、スルホン化ＥＰＤＭ、スチレンブタジエンゴム（ＳＢＲ）、フッ素ゴム等のエラストマー；多糖類高分子等が挙げられる。 Binders include, for example, fluorine resins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), thermoplastic resins such as polyethylene, polypropylene, polyacryl, and polyimide; ethylene-propylene-diene rubber (EPDM), sulfone Elastomers such as modified EPDM, styrene-butadiene rubber (SBR) and fluororubber; polysaccharide polymers and the like.
　正極合剤層におけるバインダの含有量は、１質量％以上１０質量％以下が好ましく、３質量％以上９質量％以下がより好ましい。バインダの含有量を上記の範囲とすることで、正極活物質を安定して保持することができる。 The content of the binder in the positive electrode mixture layer is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 9% by mass or less. By setting the binder content within the above range, the positive electrode active material can be stably retained.
　増粘剤としては、例えば、カルボキシメチルセルロース（ＣＭＣ）、メチルセルロース等の多糖類高分子が挙げられる。増粘剤がリチウム等と反応する官能基を有する場合、予めメチル化等によりこの官能基を失活させてもよい。 Examples of thickeners include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose. When the thickener has a functional group that reacts with lithium or the like, the functional group may be previously deactivated by methylation or the like.
　フィラーは、特に限定されない。フィラーとしては、ポリプロピレン、ポリエチレン等のポリオレフィン、二酸化ケイ素、アルミナ、二酸化チタン、酸化カルシウム、酸化ストロンチウム、酸化バリウム、酸化マグネシウム、アルミノケイ酸塩等の無機酸化物、水酸化マグネシウム、水酸化カルシウム、水酸化アルミニウム等の水酸化物、炭酸カルシウム等の炭酸塩、フッ化カルシウム、フッ化バリウム、硫酸バリウム等の難溶性のイオン結晶、窒化アルミニウム、窒化ケイ素等の窒化物、タルク、モンモリロナイト、ベーマイト、ゼオライト、アパタイト、カオリン、ムライト、スピネル、オリビン、セリサイト、ベントナイト、マイカ等の鉱物資源由来物質又はこれらの人造物等が挙げられる。 The filler is not particularly limited. Fillers include polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, alumina, titanium dioxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide and aluminosilicate, magnesium hydroxide, calcium hydroxide, hydroxide Hydroxides such as aluminum, carbonates such as calcium carbonate, poorly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium sulfate, nitrides such as aluminum nitride and silicon nitride, talc, montmorillonite, boehmite, zeolite, Mineral resource-derived substances such as apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof may be used.
　正極合剤層は、Ｂ、Ｎ、Ｆ、Ｃｌ、Ｂｒ、Ｉ等の典型非金属元素、Ｌｉ、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｚｎ、Ｇａ、Ｇｅ、Ｓｎ、Ｓｒ、Ｂａ等の典型金属元素、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｍｏ、Ｚｒ、Ｎｂ、Ｗ等の遷移金属元素を正極活物質、リン元素（例えばリンのオキソ酸又はその誘導体）、導電剤、バインダ、増粘剤、フィラー以外の成分として含有してもよい。 The positive electrode mixture layer contains typical nonmetallic elements such as B, N, F, Cl, Br, and I, and typical elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, and Ba. Metal elements, transition metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Nb, and W are used as positive electrode active materials, and phosphorus elements (for example, phosphorus oxoacids or derivatives thereof) , a conductive agent, a binder, a thickener, and a component other than a filler.
［負極］
　負極は、負極活物質層を有する。負極は、さらに負極基材と、当該負極基材と負極活物質層との間に配される中間層とを有していてもよい。中間層の構成は特に限定されず、例えば上記正極で例示した構成から選択することができる。 [Negative electrode]
The negative electrode has a negative electrode active material layer. The negative electrode may further include a negative electrode substrate and an intermediate layer interposed between the negative electrode substrate and the negative electrode active material layer. The structure of the intermediate layer is not particularly limited, and can be selected from, for example, the structures exemplified for the positive electrode.
　負極基材は、導電性を有する。負極基材の材質としては、銅、ニッケル、ステンレス鋼、ニッケルメッキ鋼等の金属又はこれらの合金、炭素質材料等が用いられる。これらの中でもステンレス鋼、銅又は銅合金が好ましい。負極基材としては、箔、蒸着膜、メッシュ、多孔質材料等が挙げられ、コストの観点から箔が好ましい。したがって、負極基材としてはステンレス鋼箔、銅箔又は銅合金箔が好ましい。銅箔の例としては、圧延銅箔、電解銅箔等が挙げられる。 The negative electrode base material has conductivity. As materials for the negative electrode substrate, metals such as copper, nickel, stainless steel, nickel-plated steel, alloys thereof, carbonaceous materials, and the like are used. Among these, stainless steel, copper, or copper alloys are preferred. Examples of negative electrode substrates include foils, deposited films, meshes, porous materials, and the like, and foils are preferable from the viewpoint of cost. Therefore, stainless steel foil, copper foil, or copper alloy foil is preferable as the negative electrode substrate. Examples of copper foil include rolled copper foil and electrolytic copper foil.
　負極基材の平均厚さは、２μｍ以上３５μｍ以下が好ましく、３μｍ以上３０μｍ以下がより好ましく、４μｍ以上２５μｍ以下がさらに好ましく、５μｍ以上２０μｍ以下が特に好ましい。負極基材の平均厚さを上記の範囲とすることで、負極基材の強度を高めつつ、二次電池の体積当たりのエネルギー密度を高めることができる。 The average thickness of the negative electrode substrate is preferably 2 μm or more and 35 μm or less, more preferably 3 μm or more and 30 μm or less, even more preferably 4 μm or more and 25 μm or less, and particularly preferably 5 μm or more and 20 μm or less. By setting the average thickness of the negative electrode substrate within the above range, the energy density per volume of the secondary battery can be increased while increasing the strength of the negative electrode substrate.
　負極活物質層は、リチウム金属を含む。リチウム金属は、負極活物質として機能する成分である。リチウム金属は、実質的にリチウム元素のみからなる純リチウム金属として存在してもよいし、他の金属元素を含むリチウム合金として存在してもよい。これらを合わせて「リチウム金属」という。リチウム合金としては、リチウム金合金、リチウムスズ合金、リチウム銀合金、リチウム亜鉛合金、リチウムカルシウム合金、リチウムアルミニウム合金、リチウムマグネシウム合金、リチウムインジウム合金等が挙げられる。リチウム合金は、リチウム元素以外の複数の金属元素を含んでいてもよい。 The negative electrode active material layer contains lithium metal. Lithium metal is a component that functions as a negative electrode active material. Lithium metal may exist as pure lithium metal consisting essentially of the lithium element, or may exist as a lithium alloy containing other metal elements. Together they are called "lithium metal". Lithium alloys include lithium gold alloys, lithium tin alloys, lithium silver alloys, lithium zinc alloys, lithium calcium alloys, lithium aluminum alloys, lithium magnesium alloys, lithium indium alloys, and the like. The lithium alloy may contain multiple metal elements other than the lithium element.
　負極活物質層は、実質的にリチウム金属のみからなる層であってもよい。負極活物質層におけるリチウム金属の含有量は、９０質量％以上であってもよく、９９質量％以上であってもよく、１００質量％であってもよい。負極活物質層におけるリチウム金属の含有量が上記下限以上であることで、二次電池のエネルギー密度をより高めることができる。 The negative electrode active material layer may be a layer consisting essentially of lithium metal. The lithium metal content in the negative electrode active material layer may be 90% by mass or more, 99% by mass or more, or 100% by mass. When the content of lithium metal in the negative electrode active material layer is at least the above lower limit, the energy density of the secondary battery can be further increased.
　負極活物質層は、リチウム金属箔（リチウム合金箔を含む）であってもよい。負極活物質層は、無孔質の層（中実の層）であってもよい。負極活物質層の平均厚さは、５μｍ以上６００μｍ以下が好ましく、１０μｍ以上４００μｍ以下がより好ましく、３０μｍ以上２００μｍ以下がさらに好ましい。負極活物質層の平均厚さを上記の範囲とすることで、負極活物質層の高エネルギー密度化と製造性を両立できる。 The negative electrode active material layer may be lithium metal foil (including lithium alloy foil). The negative electrode active material layer may be a non-porous layer (solid layer). The average thickness of the negative electrode active material layer is preferably 5 μm or more and 600 μm or less, more preferably 10 μm or more and 400 μm or less, and even more preferably 30 μm or more and 200 μm or less. By setting the average thickness of the negative electrode active material layer within the above range, it is possible to achieve both high energy density and manufacturability of the negative electrode active material layer.
［セパレータ］
　セパレータは、公知のセパレータの中から適宜選択できる。セパレータとして、例えば、基材層のみからなるセパレータ、基材層の一方の面又は双方の面に耐熱粒子とバインダとを含む耐熱層が形成されたセパレータ等を使用することができる。セパレータの基材層の形状としては、例えば、織布、不織布、多孔質樹脂フィルム等が挙げられる。これらの形状の中でも、強度の観点から多孔質樹脂フィルムが好ましく、非水電解質の保液性の観点から不織布が好ましい。セパレータの基材層の材料としては、シャットダウン機能の観点から例えばポリエチレン、ポリプロピレン等のポリオレフィンが好ましく、耐酸化分解性の観点から例えばポリイミドやアラミド等が好ましい。セパレータの基材層として、これらの樹脂を複合した材料を用いてもよい。 [Separator]
The separator can be appropriately selected from known separators. As the separator, for example, a separator consisting of only a substrate layer, a separator having a heat-resistant layer containing heat-resistant particles and a binder formed on one or both surfaces of a substrate layer, or the like can be used. Examples of the shape of the base layer of the separator include woven fabric, nonwoven fabric, and porous resin film. Among these shapes, a porous resin film is preferred from the viewpoint of strength, and a non-woven fabric is preferred from the viewpoint of non-aqueous electrolyte retention. As the material for the base layer of the separator, polyolefins such as polyethylene and polypropylene are preferable from the viewpoint of shutdown function, and polyimide, aramid, and the like are preferable from the viewpoint of oxidative decomposition resistance. A material obtained by combining these resins may be used as the base material layer of the separator.
　耐熱層に含まれる耐熱粒子は、１気圧の空気雰囲気下で室温から５００℃まで昇温したときの質量減少が５％以下であるものが好ましく、室温から８００℃まで昇温したときの質量減少が５％以下であるものがさらに好ましい。質量減少が所定以下である材料として無機化合物が挙げられる。無機化合物として、例えば、酸化鉄、酸化ケイ素、酸化アルミニウム、酸化チタン、酸化ジルコニウム、酸化カルシウム、酸化ストロンチウム、酸化バリウム、酸化マグネシウム、アルミノケイ酸塩等の酸化物；窒化アルミニウム、窒化ケイ素等の窒化物；炭酸カルシウム等の炭酸塩；硫酸バリウム等の硫酸塩；フッ化カルシウム、フッ化バリウム、チタン酸バリウム等の難溶性のイオン結晶；シリコン、ダイヤモンド等の共有結合性結晶；タルク、モンモリロナイト、ベーマイト、ゼオライト、アパタイト、カオリン、ムライト、スピネル、オリビン、セリサイト、ベントナイト、マイカ等の鉱物資源由来物質又はこれらの人造物等が挙げられる。無機化合物として、これらの物質の単体又は複合体を単独で用いてもよく、２種以上を混合して用いてもよい。これらの無機化合物の中でも、蓄電素子の安全性の観点から、酸化ケイ素、酸化アルミニウム、又はアルミノケイ酸塩が好ましい。 The heat-resistant particles contained in the heat-resistant layer preferably have a mass loss of 5% or less when the temperature is raised from room temperature to 500 ° C. in an air atmosphere of 1 atm, and the mass loss when the temperature is raised from room temperature to 800 ° C. is more preferably 5% or less. An inorganic compound can be mentioned as a material whose mass reduction is less than or equal to a predetermined value. Examples of inorganic compounds include oxides such as iron oxide, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, and aluminosilicate; nitrides such as aluminum nitride and silicon nitride. carbonates such as calcium carbonate; sulfates such as barium sulfate; sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium titanate; covalent crystals such as silicon and diamond; Mineral resource-derived substances such as zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof. As the inorganic compound, a single substance or a composite of these substances may be used alone, or two or more of them may be mixed and used. Among these inorganic compounds, silicon oxide, aluminum oxide, or aluminosilicate is preferable from the viewpoint of the safety of the electric storage device.
　セパレータの空孔率は、強度の観点から８０体積％以下が好ましく、放電性能の観点から２０体積％以上が好ましい。ここで、「空孔率」とは、体積基準の値であり、水銀ポロシメータでの測定値を意味する。 The porosity of the separator is preferably 80% by volume or less from the viewpoint of strength, and preferably 20% by volume or more from the viewpoint of discharge performance. Here, the "porosity" is a volume-based value and means a value measured with a mercury porosimeter.
　セパレータとして、ポリマーと非水電解質とで構成されるポリマーゲルを用いてもよい。ポリマーとして、例えば、ポリアクリロニトリル、ポリエチレンオキシド、ポリプロピレンオキシド、ポリメチルメタアクリレート、ポリビニルアセテート、ポリビニルピロリドン、ポリフッ化ビニリデン等が挙げられる。ポリマーゲルを用いると、漏液を抑制する効果がある。セパレータとして、上述したような多孔質樹脂フィルム又は不織布等とポリマーゲルを併用してもよい。 A polymer gel composed of a polymer and a non-aqueous electrolyte may be used as the separator. Examples of polymers include polyacrylonitrile, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyvinylidene fluoride, and the like. The use of polymer gel has the effect of suppressing liquid leakage. As the separator, a polymer gel may be used in combination with the porous resin film or non-woven fabric as described above.
［非水電解質］
　非水電解質は化合物ａを含む。非水電解質には、非水電解液を用いてもよい。非水電解液は、非水溶媒と、この非水溶媒に溶解されている電解質塩とを含む。非水電解液は、非水溶媒と電解質塩以外に、添加剤を含んでもよい。化合物ａは非水電解質中に、電解質塩として含まれてもよく、添加剤として含まれてもよい。上記電解質塩及び上記添加剤の少なくとも一方に化合物ａが含まれる。 [Non-aqueous electrolyte]
The non-aqueous electrolyte contains compound a. A non-aqueous electrolyte may be used as the non-aqueous electrolyte. The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous electrolyte may contain additives in addition to the non-aqueous solvent and electrolyte salt. The compound a may be contained as an electrolyte salt or as an additive in the non-aqueous electrolyte. At least one of the electrolyte salt and the additive contains the compound a.
　非水溶媒としては、公知の非水溶媒の中から適宜選択できる。非水溶媒としては、環状カーボネート、鎖状カーボネート、カルボン酸エステル、リン酸エステル、スルホン酸エステル、エーテル、アミド、ニトリル等が挙げられる。非水溶媒として、これらの化合物に含まれる水素原子の一部がハロゲンに置換されたものを用いてもよい。 The non-aqueous solvent can be appropriately selected from known non-aqueous solvents. Non-aqueous solvents include cyclic carbonates, chain carbonates, carboxylic acid esters, phosphoric acid esters, sulfonic acid esters, ethers, amides, nitriles and the like. As the non-aqueous solvent, those in which some of the hydrogen atoms contained in these compounds are substituted with halogens may be used.
　環状カーボネートとしては、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート（ＢＣ）、ビニレンカーボネート（ＶＣ）、ビニルエチレンカーボネート（ＶＥＣ）、クロロエチレンカーボネート、フルオロエチレンカーボネート（ＦＥＣ）、ジフルオロエチレンカーボネート（ＤＦＥＣ）、スチレンカーボネート、１－フェニルビニレンカーボネート、１，２－ジフェニルビニレンカーボネート等が挙げられる。これらの中でもＦＥＣが好ましい。 Cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinylethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), difluoroethylene carbonate. (DFEC), styrene carbonate, 1-phenylvinylene carbonate, 1,2-diphenylvinylene carbonate and the like. Among these, FEC is preferred.
　鎖状カーボネートとしては、ジエチルカーボネート（ＤＥＣ）、ジメチルカーボネート（ＤＭＣ）、エチルメチルカーボネート（ＥＭＣ）、ジフェニルカーボネート、トリフルオロエチルメチルカーボネート（ＴＦＥＭＣ）、ビス（トリフルオロエチル）カーボネート等が挙げられる。これらの中でもＤＭＣ、ＴＦＥＭＣが好ましい。 Examples of chain carbonates include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diphenyl carbonate, trifluoroethylmethyl carbonate (TFEMC), bis(trifluoroethyl) carbonate, and the like. Among these, DMC and TFEMC are preferred.
　非水溶媒として、環状カーボネート又は鎖状カーボネートを用いることが好ましく、環状カーボネートと鎖状カーボネートとを併用することがより好ましい。環状カーボネートを用いることで、電解質塩の解離を促進して非水電解液のイオン伝導度を向上させることができる。鎖状カーボネートを用いることで、非水電解液の粘度を低く抑えることができる。環状カーボネートと鎖状カーボネートとを併用する場合、環状カーボネートと鎖状カーボネートとの体積比率（環状カーボネート：鎖状カーボネート）としては、例えば、５：９５から５０：５０の範囲とすることが好ましい。 As the non-aqueous solvent, it is preferable to use a cyclic carbonate or a chain carbonate, and it is more preferable to use a combination of a cyclic carbonate and a chain carbonate. By using a cyclic carbonate, it is possible to promote the dissociation of the electrolyte salt and improve the ionic conductivity of the non-aqueous electrolyte. By using a chain carbonate, the viscosity of the non-aqueous electrolyte can be kept low. When a cyclic carbonate and a chain carbonate are used together, the volume ratio of the cyclic carbonate to the chain carbonate (cyclic carbonate:chain carbonate) is preferably in the range of, for example, 5:95 to 50:50.
　電解質塩としては、公知の電解質塩から適宜選択できる。電解質塩としては、リチウム塩、ナトリウム塩、カリウム塩、マグネシウム塩、オニウム塩等が挙げられる。これらの中でもリチウム塩が好ましい。 The electrolyte salt can be appropriately selected from known electrolyte salts. Examples of electrolyte salts include lithium salts, sodium salts, potassium salts, magnesium salts, onium salts and the like. Among these, lithium salts are preferred.
　リチウム塩としては、ＬｉＰＦ６、ジフルオロリン酸リチウム（ＬｉＤＦＰ）、モノフルオロリン酸リチウム、ＬｉＢＦ４、ＬｉＣｌＯ４、ＬｉＮ（ＳＯ２Ｆ）２等の無機リチウム塩、リチウムビス（オキサレート）ボレート（ＬｉＢＯＢ）、リチウムジフルオロオキサレートボレート（ＬｉＤＦＯＢ）、リチウムジフルオロビス（オキサレート）ホスフェート（ＬｉＦＯＰ）、リチウムテトラフルオロオキサレートホスフェート等のシュウ酸リチウム塩、ＬｉＳＯ３ＣＦ３、ＬｉＮ（ＳＯ２ＣＦ３）２、ＬｉＮ（ＳＯ２Ｃ２Ｆ５）２、ＬｉＮ（ＳＯ２ＣＦ３）（ＳＯ２Ｃ４Ｆ９）、ＬｉＣ（ＳＯ２ＣＦ３）３、ＬｉＣ（ＳＯ２Ｃ２Ｆ５）３等のハロゲン化炭化水素基を有するリチウム塩等が挙げられる。これらの中でも、無機リチウム塩が好ましく、ＬｉＰＦ６がより好ましい。上記ジフルオロリン酸リチウム（ＬｉＤＦＰ）、モノフルオロリン酸リチウム、リチウムジフルオロオキサレートボレート（ＬｉＤＦＯＢ）、リチウムジフルオロビス（オキサレート）ホスフェート（ＬｉＦＯＰ）及びリチウムテトラフルオロオキサレートホスフェートは、電解質塩としての化合物ａである。このように、化合物ａを電解質塩として用いてもよい。 Lithium salts include inorganic lithium salts such as LiPF 6 , lithium difluorophosphate (LiDFP), lithium monofluorophosphate, LiBF 4 , LiClO 4 , LiN(SO 2 F) 2 , and lithium bis(oxalate)borate (LiBOB). , lithium difluorooxalateborate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiFOP), lithium oxalate salts such as lithium tetrafluorooxalate phosphate, LiSO3CF3 , LiN( SO2CF3 ) 2 , LiN ( Halogenated hydrocarbons such as SO2C2F5 ) 2 , LiN ( SO2CF3 ) ( SO2C4F9 ) , LiC ( SO2CF3 ) 3 , LiC ( SO2C2F5 ) 3 and a lithium salt having a group. Among these, inorganic lithium salts are preferred, and LiPF6 is more preferred. The lithium difluorophosphate (LiDFP), lithium monofluorophosphate, lithium difluorooxalate borate (LiDFOB), lithium difluorobis(oxalate) phosphate (LiFOP) and lithium tetrafluorooxalate phosphate are compound a as the electrolyte salt. be. Thus, compound a may be used as an electrolyte salt.
　非水電解液における電解質塩の含有量は、２０℃１気圧下において、０．１ｍｏｌ／ｄｍ３以上２．５ｍｏｌ／ｄｍ３以下であると好ましく、０．３ｍｏｌ／ｄｍ３以上２．０ｍｏｌ／ｄｍ３以下であるとより好ましく、０．５ｍｏｌ／ｄｍ３以上１．７ｍｏｌ／ｄｍ３以下であるとさらに好ましく、０．７ｍｏｌ／ｄｍ３以上１．５ｍｏｌ／ｄｍ３以下であると特に好ましい。電解質塩の含有量を上記の範囲とすることで、非水電解液のイオン伝導度を高めることができる。 The content of the electrolyte salt in the non-aqueous electrolyte is preferably 0.1 mol/dm3 or more and 2.5 mol/dm3 or less , and 0.3 mol/dm3 or more and 2.0 mol/dm3 or less at 20 °C and 1 atm. It is more preferably 3 or less, more preferably 0.5 mol/dm 3 or more and 1.7 mol/dm 3 or less, and particularly preferably 0.7 mol/dm 3 or more and 1.5 mol/dm 3 or less. By setting the content of the electrolyte salt within the above range, the ionic conductivity of the non-aqueous electrolyte can be increased.
　化合物ａは上記のように電解質塩として用いる他、添加剤として用いてもよい。添加剤としての化合物ａは、酸素元素と、フッ素元素と、リン元素及びホウ素元素のうち少なくとも一方とを含む。上記化合物ａとしては、リチウム元素と酸素元素とフッ素元素とを含むリチウムのリン酸塩、リチウム元素とホウ素元素とフッ素元素とを含むリチウムのシュウ酸塩及びリチウム元素とリン元素とフッ素元素とを含むリチウムのシュウ酸塩が好ましく、これらの中でもジフルオロリン酸リチウム（ＬｉＤＦＰ）、モノフルオロリン酸リチウム、リチウムジフルオロオキサレートボレート（ＬｉＤＦＯＢ）、リチウムジフルオロビス（オキサレート）ホスフェート（ＬｉＦＯＰ）及びリチウムテトラフルオロオキサレートホスフェートがより好ましく、ジフルオロリン酸リチウム（ＬｉＤＦＰ）又はリチウムジフルオロオキサレートボレート（ＬｉＤＦＯＢ）がさらに好ましい。上記化合物ａとしては、リチウム元素と酸素元素とフッ素元素とを含むリチウムのリン酸塩が、内部短絡の発生を遅延させる点から好ましい。このように非水電解液が上記化合物ａを含むことにより、負極の表面に良好な上記化合物ａに由来する被膜が形成されやすい。 In addition to being used as an electrolyte salt as described above, compound a may also be used as an additive. The compound a as an additive contains oxygen element, fluorine element, and at least one of phosphorus element and boron element. Examples of the compound a include a lithium phosphate containing lithium element, oxygen element and fluorine element, a lithium oxalate containing lithium element, boron element and fluorine element, and lithium element, phosphorus element and fluorine element. Lithium oxalates containing, among others, lithium difluorophosphate (LiDFP), lithium monofluorophosphate, lithium difluorooxalateborate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiFOP) and lithium tetrafluorooxalate Late phosphates are more preferred, and lithium difluorophosphate (LiDFP) or lithium difluorooxalateborate (LiDFOB) are even more preferred. As the compound a, a lithium phosphate containing lithium element, oxygen element and fluorine element is preferable from the viewpoint of delaying the occurrence of an internal short circuit. When the non-aqueous electrolyte contains the compound a in this way, a good film derived from the compound a is easily formed on the surface of the negative electrode.
　非水電解液は、上記化合物ａ以外に、さらに他の添加剤を含んでもよい。上記他の添加剤としては、例えば、フルオロエチレンカーボネート（ＦＥＣ）、ジフルオロエチレンカーボネート（ＤＦＥＣ）等のハロゲン化炭酸エステル；リチウムビス（オキサレート）ボレート（ＬｉＢＯＢ）等のシュウ酸塩；リチウムビス（フルオロスルホニル）イミド（ＬｉＦＳＩ）等のイミド塩；ビフェニル、アルキルビフェニル、ターフェニル、ターフェニルの部分水素化体、シクロヘキシルベンゼン、ｔ－ブチルベンゼン、ｔ－アミルベンゼン、ジフェニルエーテル、ジベンゾフラン等の芳香族化合物；２－フルオロビフェニル、ｏ－シクロヘキシルフルオロベンゼン、ｐ－シクロヘキシルフルオロベンゼン等の前記芳香族化合物の部分ハロゲン化物；２，４－ジフルオロアニソール、２，５－ジフルオロアニソール、２，６－ジフルオロアニソール、３，５－ジフルオロアニソール等のハロゲン化アニソール化合物；ビニレンカーボネート、メチルビニレンカーボネート、エチルビニレンカーボネート、無水コハク酸、無水グルタル酸、無水マレイン酸、無水シトラコン酸、無水グルタコン酸、無水イタコン酸、シクロヘキサンジカルボン酸無水物；亜硫酸エチレン、亜硫酸プロピレン、亜硫酸ジメチル、メタンスルホン酸メチル、ブスルファン、トルエンスルホン酸メチル、硫酸ジメチル、硫酸エチレン、スルホラン、ジメチルスルホン、ジエチルスルホン、ジメチルスルホキシド、ジエチルスルホキシド、テトラメチレンスルホキシド、ジフェニルスルフィド、４，４’－ビス（２，２－ジオキソ－１，３，２－ジオキサチオラン）、４－メチルスルホニルオキシメチル－２，２－ジオキソ－１，３，２－ジオキサチオラン、チオアニソール、ジフェニルジスルフィド、ジピリジニウムジスルフィド、１，３－プロペンスルトン、１，３－プロパンスルトン、１，４－ブタンスルトン、１，４－ブテンスルトン、パーフルオロオクタン、ホウ酸トリストリメチルシリル、リン酸トリストリメチルシリル、チタン酸テトラキストリメチルシリル等が挙げられる。これら添加剤は、１種を単独で用いてもよく、２種以上を混合して用いてもよい。 The non-aqueous electrolyte may further contain other additives in addition to the compound a. Examples of the other additives include halogenated carbonates such as fluoroethylene carbonate (FEC) and difluoroethylene carbonate (DFEC); oxalates such as lithium bis(oxalate)borate (LiBOB); lithium bis(fluorosulfonyl); ) imide salts such as imide (LiFSI); biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran and other aromatic compounds; 2- Partial halides of the above aromatic compounds such as fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, 3,5- Halogenated anisole compounds such as difluoroanisole; vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride; ethylene sulfite, propylene sulfite, dimethyl sulfite, methyl methanesulfonate, busulfan, methyl toluenesulfonate, dimethyl sulfate, ethylene sulfate, sulfolane, dimethylsulfone, diethylsulfone, dimethylsulfoxide, diethylsulfoxide, tetramethylenesulfoxide, diphenylsulfide, 4, 4'-bis(2,2-dioxo-1,3,2-dioxathiolane), 4-methylsulfonyloxymethyl-2,2-dioxo-1,3,2-dioxathiolane, thioanisole, diphenyl disulfide, dipyridinium disulfide , 1,3-propenesultone, 1,3-propanesultone, 1,4-butanesultone, 1,4-butenesultone, perfluorooctane, tristrimethylsilyl borate, tristrimethylsilyl phosphate, tetrakistrimethylsilyl titanate, and the like. These additives may be used singly or in combination of two or more.
　非水電解液に含まれる上記化合物ａの含有量は、非水電解液全体の質量に対して０．０１質量％以上１０質量％以下であると好ましく、０．１質量％以上７質量％以下であるとより好ましく、０．２質量％以上６質量％以下であるとさらに好ましく、０．３質量％以上５質量％以下であると特に好ましい。非水電解液に含まれる上記化合物の含有量を、上記の範囲とすることで、負極における上記化合物ａに由来する被膜がさらに均一かつ良好に形成されやすい。 The content of the compound a contained in the non-aqueous electrolyte is preferably 0.01% by mass or more and 10% by mass or less with respect to the total mass of the non-aqueous electrolyte, and 0.1% by mass or more and 7% by mass or less. is more preferably 0.2% by mass or more and 6% by mass or less, and particularly preferably 0.3% by mass or more and 5% by mass or less. By setting the content of the compound contained in the non-aqueous electrolyte within the above range, the film derived from the compound a on the negative electrode can be more uniformly and favorably formed.
　非水電解液に含まれる上記化合物ａ及び上記他の添加剤の合計含有量は、非水電解液全体の質量に対して０．０１質量％以上１０質量％以下であると好ましく、０．１質量％以上９質量％以下であるとより好ましく、０．２質量％以上８質量％以下であるとさらに好ましく、０．３質量％以上７質量％以下であると特に好ましい。上記化合物ａ及び上記他の添加剤の合計含有量を上記の範囲とすることで、高温保存後の容量維持性能又はサイクル性能を向上させたり、安全性をより向上させたりすることができる。 The total content of the compound a and the other additives contained in the non-aqueous electrolyte is preferably 0.01% by mass or more and 10% by mass or less with respect to the total mass of the non-aqueous electrolyte, and 0.1 It is more preferably 0.2% to 8% by mass, and particularly preferably 0.3% to 7% by mass. By setting the total content of the compound a and the other additives within the above range, it is possible to improve capacity retention performance or cycle performance after high-temperature storage, or to further improve safety.
　非水電解質には、固体電解質を用いてもよく、非水電解液と固体電解質とを併用してもよい。 A solid electrolyte may be used as the non-aqueous electrolyte, or a non-aqueous electrolyte and a solid electrolyte may be used together.
　固体電解質としては、リチウム、ナトリウム、カルシウム等のイオン伝導性を有し、常温（例えば１５℃から２５℃）において固体である任意の材料から選択できる。固体電解質としては、例えば、硫化物固体電解質、酸化物固体電解質、及び酸窒化物固体電解質、ポリマー固体電解質等が挙げられる。 The solid electrolyte can be selected from any material that has ion conductivity, such as lithium, sodium, and calcium, and is solid at room temperature (for example, 15°C to 25°C). Examples of solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, oxynitride solid electrolytes, and polymer solid electrolytes.
　硫化物固体電解質としては、リチウム二次電池の場合、例えば、Ｌｉ２Ｓ－Ｐ２Ｓ５、ＬｉＩ－Ｌｉ２Ｓ－Ｐ２Ｓ５、Ｌｉ１０Ｇｅ－Ｐ２Ｓ１２等が挙げられる。 Examples of sulfide solid electrolytes for lithium secondary batteries include Li 2 SP 2 S 5 , LiI—Li 2 SP 2 S 5 , Li 10 Ge—P 2 S 12 and the like.
　本実施形態の非水電解質蓄電素子の形状については特に限定されるものではなく、例えば、円筒型電池、角型電池、扁平型電池、コイン型電池、ボタン型電池等が挙げられる。
　図１に角型電池の一例としての非水電解質蓄電素子１を示す。なお、同図は、容器内部を透視した図としている。セパレータを挟んで巻回された正極及び負極を有する電極体２が角型の容器３に収納される。正極は正極リード４１を介して正極端子４と電気的に接続されている。負極は負極リード５１を介して負極端子５と電気的に接続されている。 The shape of the non-aqueous electrolyte storage element of the present embodiment is not particularly limited, and examples thereof include cylindrical batteries, rectangular batteries, flat batteries, coin batteries, button batteries, and the like.
FIG. 1 shows a non-aqueous electrolyte storage element 1 as an example of a square battery. In addition, the same figure is taken as the figure which saw through the inside of a container. An electrode body 2 having a positive electrode and a negative electrode wound with a separator sandwiched therebetween is housed in a rectangular container 3 . The positive electrode is electrically connected to the positive electrode terminal 4 via a positive electrode lead 41 . The negative electrode is electrically connected to the negative terminal 5 via a negative lead 51 .
＜蓄電装置の構成＞
　本実施形態の非水電解質蓄電素子は、電気自動車（ＥＶ）、ハイブリッド自動車（ＨＥＶ）、プラグインハイブリッド自動車（ＰＨＥＶ）等の自動車用電源、パーソナルコンピュータ、通信端末等の電子機器用電源、又は電力貯蔵用電源等に、複数の非水電解質蓄電素子１を集合して構成した蓄電ユニット（バッテリーモジュール）として搭載することができる。この場合、蓄電ユニットに含まれる少なくとも一つの非水電解質蓄電素子に対して、本発明の技術が適用されていればよい。
　本発明の一実施形態に係る蓄電装置は、非水電解質蓄電素子を二以上備え、且つ上記実施の形態に係る非水電解質蓄電素子を一以上備える（以下、「第二の実施形態」という。）。第二の実施形態に係る蓄電装置に含まれる少なくとも一つの非水電解質蓄電素子に対して、本発明の一実施形態に係る技術が適用されていればよく、上記本発明の一実施形態に係る非水電解質蓄電素子を一備え、且つ上記本発明の一実施形態に係らない非水電解質蓄電素子を一以上備えていてもよく、上記本発明の一実施形態に係る非水電解質蓄電素子を二以上備えていてもよい。図２に、電気的に接続された二以上の非水電解質蓄電素子１が集合した蓄電ユニット２０をさらに集合した第二の実施形態に係る蓄電装置３０の一例を示す。蓄電装置３０は、二以上の非水電解質蓄電素子１を電気的に接続するバスバ（図示せず）、二以上の蓄電ユニット２０を電気的に接続するバスバ（図示せず）等を備えていてもよい。蓄電ユニット２０又は蓄電装置３０は、一以上の非水電解質蓄電素子の状態を監視する状態監視装置（図示せず）を備えていてもよい。 <Configuration of power storage device>
The non-aqueous electrolyte storage element of the present embodiment is a power source for automobiles such as electric vehicles (EV), hybrid vehicles (HEV), and plug-in hybrid vehicles (PHEV), power sources for electronic devices such as personal computers and communication terminals, or electric power It can be installed in a power source for storage or the like as a power storage unit (battery module) configured by collecting a plurality of non-aqueous electrolyte power storage elements 1 . In this case, the technology of the present invention may be applied to at least one non-aqueous electrolyte storage element included in the storage unit.
A power storage device according to an embodiment of the present invention includes two or more nonaqueous electrolyte power storage elements and one or more nonaqueous electrolyte power storage elements according to the above embodiments (hereinafter referred to as "second embodiment"). ). It is sufficient that the technology according to one embodiment of the present invention is applied to at least one non-aqueous electrolyte power storage element included in the power storage device according to the second embodiment. One non-aqueous electrolyte storage element may be provided, and one or more non-aqueous electrolyte storage elements according to the above embodiment may be provided, and two non-aqueous electrolyte storage elements according to the above embodiment may be provided. You may have more. FIG. 2 shows an example of a power storage device 30 according to the second embodiment, in which power storage units 20 in which two or more electrically connected non-aqueous electrolyte power storage elements 1 are assembled are further assembled. The power storage device 30 includes a bus bar (not shown) electrically connecting two or more non-aqueous electrolyte power storage elements 1, a bus bar (not shown) electrically connecting two or more power storage units 20, and the like. good too. The power storage unit 20 or the power storage device 30 may include a state monitoring device (not shown) that monitors the state of one or more non-aqueous electrolyte power storage elements.
＜非水電解質蓄電素子の製造方法＞
　本実施形態の非水電解質蓄電素子の製造方法は、公知の方法から適宜選択できる。当該製造方法は、例えば、リン元素を含む正極合剤を有する正極を準備することと、リチウム金属を含む負極を準備することと、化合物ａを含む非水電解質を準備することとを備える。 <Method for producing non-aqueous electrolyte storage element>
A method for manufacturing the non-aqueous electrolyte storage element of the present embodiment can be appropriately selected from known methods. The manufacturing method includes, for example, preparing a positive electrode having a positive electrode mixture containing elemental phosphorus, preparing a negative electrode containing lithium metal, and preparing a non-aqueous electrolyte containing compound a.
　リン元素を含む正極合剤を有する正極を準備することは、リン元素を含む正極合剤を有する正極を作製することであってもよい。正極の作製は、例えば正極基材に直接又は中間層を介して、正極合剤ペーストを塗布し、乾燥させることにより行うことができる。上記正極合剤ペーストには、リン元素が含まれる。上記正極合剤層には、さらに正極活物質、及び任意成分である導電剤、バインダ、増粘剤、フィラー等の正極合剤を構成する各成分が含まれる。 Preparing a positive electrode having a positive electrode mixture containing elemental phosphorus may be manufacturing a positive electrode having a positive electrode mixture containing elemental phosphorus. The positive electrode can be produced, for example, by applying the positive electrode material mixture paste directly or via an intermediate layer to the positive electrode base material and drying the paste. The positive electrode mixture paste contains a phosphorus element. The positive electrode mixture layer further contains a positive electrode active material and optional components such as a conductive agent, a binder, a thickener, and a filler, which constitute the positive electrode mixture.
　正極合剤ペーストに含まれる上記リン元素の形態としては、リンのオキソ酸が好ましく、リンのオキソ酸の中でもホスホン酸がより好ましい。正極合剤ペーストに含まれるリン元素が上記の形態であることで、正極表面に良好なリン原子を含む被膜が形成されやすい。また、このようなリン原子を含む被膜が正極表面にて形成されることにより、負極における均一かつ良好な化合物ａに由来する被膜形成が促進される。 The form of the phosphorus element contained in the positive electrode mixture paste is preferably a phosphorus oxoacid, and among the phosphorus oxoacids, phosphonic acid is more preferable. When the phosphorus element contained in the positive electrode mixture paste is in the form described above, a film containing favorable phosphorus atoms is easily formed on the surface of the positive electrode. In addition, by forming such a film containing phosphorus atoms on the surface of the positive electrode, formation of a uniform and favorable film derived from the compound a on the negative electrode is promoted.
　上記リンのオキソ酸は、正極合剤ペーストの全体の質量に対して０．１質量％以上１．０質量％以下であることが好ましく、０．２質量％以上０．８質量％以下であることがより好ましく、０．２５質量％以上０．６質量％以下であることがさらに好ましい。上記リンのオキソ酸の含有量を上記の範囲とすることで、正負両極により良好な被膜が形成されやすい。 The phosphorus oxoacid is preferably 0.1% by mass or more and 1.0% by mass or less, and 0.2% by mass or more and 0.8% by mass or less with respect to the total mass of the positive electrode mixture paste. more preferably 0.25% by mass or more and 0.6% by mass or less. By setting the content of the oxoacid of phosphorus in the above range, it is easy to form a good film on both the positive and negative electrodes.
　リチウム金属を含む負極を準備することは、リチウム金属を含む負極を作製することであってもよい。負極の作製は、例えば負極基材に直接又は中間層を介して、箔状のリチウム金属を含む負極活物質層を接着することであってもよい。 Preparing a negative electrode containing lithium metal may be manufacturing a negative electrode containing lithium metal. The production of the negative electrode may be performed, for example, by adhering a foil-shaped negative electrode active material layer containing lithium metal to the negative electrode base material directly or via an intermediate layer.
　上記化合物ａを含む非水電解質を準備することは、上記化合物ａを含む非水電解質を調製することであってもよい。非水電解質の調製は、例えば非水溶媒、電解質塩（上記化合物ａを含む場合がある）、及び添加剤（上記化合物ａを含む場合がある）を混合することにより行うことができる。なお、上記電解質塩及び上記添加剤の少なくとも一方に化合物ａが含まれる。 Preparing the non-aqueous electrolyte containing the compound a may be preparing the non-aqueous electrolyte containing the compound a. The non-aqueous electrolyte can be prepared, for example, by mixing a non-aqueous solvent, an electrolyte salt (which may contain the above compound a), and an additive (which may contain the above compound a). At least one of the electrolyte salt and the additive contains the compound a.
　当該非水電解質蓄電素子の製造方法は、上述したリン元素を含む正極合剤を有する正極を準備すること、リチウム金属を含む負極を準備すること、及び化合物ａを含む非水電解質を準備することの他、正極及び負極をセパレータを介して積層又は巻回することにより交互に重畳された電極体を形成すること、正極及び負極（電極体）を容器に収容すること、並びに上記容器に上記非水電解質を注入することを備えていてもよい。注入後、注入口を封止することにより非水電解質蓄電素子を得ることができる。 The method for manufacturing the non-aqueous electrolyte storage element includes preparing a positive electrode having the above-described positive electrode mixture containing the phosphorus element, preparing a negative electrode containing lithium metal, and preparing a non-aqueous electrolyte containing the compound a. In addition, the positive electrode and the negative electrode are laminated or wound with a separator interposed between them to form an alternately stacked electrode body, the positive electrode and the negative electrode (electrode body) are housed in a container, and the container is filled with the above-mentioned non- It may comprise injecting a water electrolyte. After the injection, a non-aqueous electrolyte storage element can be obtained by sealing the injection port.
＜その他の実施形態＞
　尚、本発明の非水電解質蓄電素子は、上記実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲内において種々変更を加えてもよい。例えば、ある実施形態の構成に他の実施形態の構成を追加することができ、また、ある実施形態の構成の一部を他の実施形態の構成又は周知技術に置き換えることができる。さらに、ある実施形態の構成の一部を削除することができる。また、ある実施形態の構成に対して周知技術を付加することができる。 <Other embodiments>
It should be noted that the non-aqueous electrolyte storage device of the present invention is not limited to the above embodiments, and various modifications may be made without departing from the gist of the present invention. For example, the configuration of another embodiment can be added to the configuration of one embodiment, and part of the configuration of one embodiment can be replaced with the configuration of another embodiment or a known technique. Furthermore, some of the configurations of certain embodiments can be deleted. Also, well-known techniques can be added to the configuration of a certain embodiment.
　上記実施形態では、非水電解質蓄電素子が充放電可能な非水電解質二次電池（例えばリチウム二次電池）として用いられる場合について説明したが、非水電解質蓄電素子の種類、形状、寸法、容量等は任意である。本発明は、種々の二次電池、電気二重層キャパシタ又はリチウムイオンキャパシタ等のキャパシタにも適用できる。 In the above embodiment, the nonaqueous electrolyte storage element is used as a chargeable/dischargeable nonaqueous electrolyte secondary battery (for example, a lithium secondary battery). etc. are optional. The present invention can also be applied to capacitors such as various secondary batteries, electric double layer capacitors, and lithium ion capacitors.
　上記実施形態では、正極及び負極がセパレータを介して積層された電極体について説明したが、電極体は、セパレータを備えなくてもよい。例えば、正極合剤層上又は負極活物質層上に導電性を有さない層が形成された状態で、正極及び負極が直接接してもよい。 In the above embodiment, the electrode body in which the positive electrode and the negative electrode are laminated with a separator interposed therebetween has been described, but the electrode body does not have to be provided with a separator. For example, the positive electrode and the negative electrode may be in direct contact with each other in a state in which a layer having no conductivity is formed on the positive electrode mixture layer or the negative electrode active material layer.
　以下、実施例によって本発明をさらに具体的に説明する。本発明は以下の実施例に限定されない。 Hereinafter, the present invention will be described more specifically by way of examples. The invention is not limited to the following examples.
［実施例１］
（正極の作製）
　正極活物質として遷移金属（Ｍｅ）に対するリチウム（Ｌｉ）のモル比（Ｌｉ／Ｍｅ）が１．３３のリチウム遷移金属複合酸化物であって、遷移金属（Ｍｅ）がニッケル（Ｎｉ）及びマンガン（Ｍｎ）であり、Ｎｉ：Ｍｎのモル比が１：２であるリチウム遷移金属複合酸化物を用いた。固形物換算の質量比で、上記正極活物質：ポリフッ化ビニリデン（ＰＶＤＦ）：アセチレンブラック（ＡＢ）：ホスホン酸＝９２．５－ｚ：３．０：４．５：ｚ（ｚ＝０．５）の割合となるよう混合し、分散剤としてＮ－メチルピロリドン（ＮＭＰ）を適量加えて粘度を調整し、正極合剤ペーストを調製した。正極基材である平均厚さ１５μｍのアルミニウム箔の片面に、上記正極ペーストを塗工し、乾燥し、プレスし、正極合剤層が配置された正極を作製した。作製した正極の正極合剤層の塗工量は、２６．５ｍｇ／ｃｍ２であり、多孔度は４０％であった。また、作製した正極は、幅３０ｍｍ、長さ４０ｍｍの矩形状とした。 [Example 1]
(Preparation of positive electrode)
A lithium-transition metal composite oxide having a molar ratio (Li/Me) of lithium (Li) to a transition metal (Me) of 1.33 as a positive electrode active material, wherein the transition metal (Me) is nickel (Ni) and manganese ( Mn) and a lithium transition metal composite oxide having a Ni:Mn molar ratio of 1:2 was used. The mass ratio in terms of solids, the positive electrode active material: polyvinylidene fluoride (PVDF): acetylene black (AB): phosphonic acid = 92.5-z: 3.0: 4.5: z (z = 0.5 ), and an appropriate amount of N-methylpyrrolidone (NMP) as a dispersing agent was added to adjust the viscosity to prepare a positive electrode mixture paste. The positive electrode paste was applied to one side of an aluminum foil having an average thickness of 15 μm, which was a positive electrode substrate, dried, and pressed to prepare a positive electrode having a positive electrode mixture layer disposed thereon. The coating amount of the positive electrode mixture layer of the prepared positive electrode was 26.5 mg/cm 2 and the porosity was 40%. Moreover, the produced positive electrode was made into a rectangular shape with a width of 30 mm and a length of 40 mm.
（負極の作製）
　幅３１ｍｍ、長さ４２ｍｍ、厚さ６００μｍのリチウム金属板を負極とした。上記リチウム金属板には、長さ方向の一方の端部のみに幅３１ｍｍ、長さ５ｍｍのステンレス鋼製の負極基材を接続した。 (Preparation of negative electrode)
A lithium metal plate having a width of 31 mm, a length of 42 mm, and a thickness of 600 μm was used as the negative electrode. A stainless steel negative electrode substrate having a width of 31 mm and a length of 5 mm was connected to the lithium metal plate only at one end in the length direction.
（非水電解質の調製）
　ＦＥＣ：ＴＦＥＭＣを３０：７０の体積比で混合した非水溶媒に、電解質塩としてＬｉＰＦ６を１．０ｍｏｌ／ｄｍ３の濃度で溶解させ、さらに添加剤として化合物ａであるジフルオロリン酸リチウム（ＬｉＤＦＰ）を非水電解質全体の質量に対して約０．５質量％の濃度で添加して飽和溶液を作製した。上記飽和溶液を非水電解質として得た。 (Preparation of non-aqueous electrolyte)
In a non-aqueous solvent obtained by mixing FEC: TFEMC at a volume ratio of 30:70, LiPF6 is dissolved as an electrolyte salt at a concentration of 1.0 mol/dm3, and lithium difluorophosphate ( LiDFP ), which is compound a, is added as an additive. ) was added at a concentration of about 0.5% by mass with respect to the total mass of the non-aqueous electrolyte to prepare a saturated solution. The above saturated solution was obtained as a non-aqueous electrolyte.
（非水電解質蓄電素子の作製）
　セパレータとして、ポリオレフィン製微多孔膜を用いた。このセパレータを介して、上記正極と上記負極とを積層することにより電極体を作製した。この電極体を、金属樹脂複合フィルム製の容器に収納し、内部に上記非水電解質を注入した後、熱溶着により封口し、パウチセルである非水電解質蓄電素子を得た。 (Preparation of non-aqueous electrolyte storage element)
A polyolefin microporous film was used as a separator. An electrode body was produced by laminating the positive electrode and the negative electrode with the separator interposed therebetween. This electrode body was placed in a container made of a metal-resin composite film, and after the non-aqueous electrolyte was injected therein, the container was sealed by thermal welding to obtain a non-aqueous electrolyte storage element, which is a pouch cell.
［実施例２及び比較例１から４］
　正極合剤ペーストのホスホン酸の混合量ｚ及び非水電解質の化合物ａである添加剤の種類を表１に示すとおりに変更した以外は実施例１と同様にして、実施例２及び比較例１から４の非水電解質蓄電素子を作製した。 [Example 2 and Comparative Examples 1 to 4]
Example 2 and Comparative Example 1 were prepared in the same manner as in Example 1, except that the mixed amount z of phosphonic acid in the positive electrode mixture paste and the type of the additive, which is the compound a in the non-aqueous electrolyte, were changed as shown in Table 1. A non-aqueous electrolyte storage device 4 was produced from the above.
［参考例１から４］
　負極活物質の種類、正極合剤ペーストのホスホン酸の混合量ｚ及び非水電解質の添加剤の種類を表１に示すとおりに変更した以外は実施例１と同様にして、参考例１から４の非水電解質蓄電素子を作製した。参考例１から４の負極の作製においては、固形物換算の質量比で、黒鉛：ＳＢＲ：ＣＭＣ＝９６．７：２．１：１．２の割合となるよう混合し、分散剤として水を含む負極合剤ペーストを作製した。この負極合剤ペーストを負極基材である銅箔の片面に塗工し、乾燥及びプレスすることで、負極を作製した。作製した負極の負極活物質層の塗工量は、２２ｍｇ／ｃｍ２であり、多孔度は３５％であった。また、作製した負極は、幅３２ｍｍ、長さ４２ｍｍの矩形状とした。 [Reference Examples 1 to 4]
Reference Examples 1 to 4 were prepared in the same manner as in Example 1, except that the type of negative electrode active material, the mixed amount z of phosphonic acid in the positive electrode mixture paste, and the type of additive in the non-aqueous electrolyte were changed as shown in Table 1. A nonaqueous electrolyte storage element was produced. In the preparation of the negative electrodes of Reference Examples 1 to 4, the mass ratio of graphite: SBR: CMC = 96.7: 2.1: 1.2 was mixed in terms of solid matter, and water was added as a dispersant. A negative electrode mixture paste containing This negative electrode mixture paste was applied to one side of a copper foil as a negative electrode base material, dried and pressed to prepare a negative electrode. The negative electrode active material layer of the prepared negative electrode had a coating amount of 22 mg/cm 2 and a porosity of 35%. Also, the produced negative electrode had a rectangular shape with a width of 32 mm and a length of 42 mm.
　実施例、比較例及び参考例の各非水電解質蓄電素子に対して、それぞれ以下の試験を実施した。 The following tests were performed on each of the non-aqueous electrolyte storage elements of Examples, Comparative Examples, and Reference Examples.
（初期充放電）
　得られた各非水電解質蓄電素子のうち、実施例１、２、及び比較例１から４の各非水電解質蓄電素子については、２５℃の温度環境下、充電終止電圧を４．７Ｖとして、０．１Ｃの充電電流で定電流充電した後、定電圧充電した。充電の終了条件は、充電電流が０．０５Ｃとなるまでとした。１０分間の休止を設けた後に、放電終止電圧を２．０Ｖとして、０．１Ｃの放電電流で定電流放電を行った。参考例１から４の各非水電解質蓄電素子については、充電終止電圧を４．６Ｖとした以外は、上記と同様の条件で初期充放電を実施した。なお、ここでの１Ｃは、正極の単位面積あたりの電流で６．０ｍＡ／ｃｍ２とした。 (initial charge/discharge)
Among the obtained non-aqueous electrolyte storage elements, the non-aqueous electrolyte storage elements of Examples 1 and 2 and Comparative Examples 1 to 4 were subjected to a charging end voltage of 4.7 V in a temperature environment of 25° C. After constant-current charging at a charging current of 0.1 C, constant-voltage charging was performed. The charging termination condition was until the charging current reached 0.05C. After a rest period of 10 minutes, a constant current discharge was performed at a discharge current of 0.1C with a final discharge voltage of 2.0V. For each of the non-aqueous electrolyte storage elements of Reference Examples 1 to 4, initial charge/discharge was performed under the same conditions as above, except that the end-of-charge voltage was set to 4.6V. Here, 1C is the current per unit area of the positive electrode and is 6.0 mA/cm 2 .
（充放電サイクル寿命試験）
　上記初期充放電を実施後の各非水電解質蓄電素子に対して充放電サイクル寿命試験を実施した。実施例１、２、及び比較例１から４の各非水電解質蓄電素子については、２５℃の温度環境下、充電終止電圧を４．７Ｖとして、０．２Ｃの充電電流で定電流充電した後、定電圧充電した。充電の終了条件は、充電電流が０．０５Ｃとなるまでとした。１０分間の休止を設けた後に、放電終止電圧を２．０Ｖとして、０．１Ｃの放電電流で定電流放電を行った。その後、１０分間の休止を設けた。これを所定の回数繰り返した。参考例１から４の各非水電解質蓄電素子については、充電終止電圧を４．６Ｖとした以外は、上記と同様の条件で充放電サイクル寿命試験を実施した。 (Charge-discharge cycle life test)
A charge/discharge cycle life test was performed on each non-aqueous electrolyte storage element after the initial charge/discharge was performed. Each of the non-aqueous electrolyte storage elements of Examples 1 and 2 and Comparative Examples 1 to 4 was subjected to constant-current charging at a charging current of 0.2 C under a temperature environment of 25° C. with a charging end voltage of 4.7 V. , constant voltage charging. The charging termination condition was until the charging current reached 0.05C. After a rest period of 10 minutes, a constant current discharge was performed at a discharge current of 0.1C with a final discharge voltage of 2.0V. A rest period of 10 minutes was then provided. This was repeated a predetermined number of times. For each of the non-aqueous electrolyte storage elements of Reference Examples 1 to 4, a charge-discharge cycle life test was performed under the same conditions as above, except that the final charge voltage was set to 4.6V.
（内部抵抗の測定）
　上記初期充放電を２サイクル実施後に内部抵抗を測定した。その後、上記充放電サイクル寿命試験を５０サイクル実施後に内部抵抗を測定した。内部抵抗の増加率（％）は、上記初期充放電実施後の内部抵抗をＲ１、上記５０サイクル実施後の内部抵抗をＲ２とした場合に、下記式１により算出した。
　（Ｒ２／Ｒ１）×１００－１００・・・１
　なお、上記内部抵抗は、放電状態で室温にて１ｋＨｚの交流抵抗を測定することにより得た値である。測定装置は、３５６０ＡＣミリオームハイテスタ（ＨＩＯＫＩ製）を用いた。 (Measurement of internal resistance)
After two cycles of the initial charge and discharge, the internal resistance was measured. After that, the internal resistance was measured after 50 cycles of the charge/discharge cycle life test. The rate of increase (%) of the internal resistance was calculated by the following formula 1, where R 1 is the internal resistance after the initial charging/discharging, and R 2 is the internal resistance after the 50 cycles.
(R 2 /R 1 )×100−100 1
The internal resistance is a value obtained by measuring AC resistance at 1 kHz at room temperature in a discharged state. A 3560 AC milliohm high tester (manufactured by Hioki) was used as a measuring device.
（内部短絡発生までのサイクル数測定）
　実施例１、実施例２及び比較例１から４の非水電解質蓄電素子に対して、内部短絡が発生するまで上記充放電サイクル寿命試験を実施し、内部短絡が発生するまでのサイクル数を測定した。短絡の発生の有無は、充放電サイクル中の充電電気量の上昇によるクーロン効率の低下により確認した。具体的には、充電電気量が、直前のサイクルの充電電気量と比較して増大し、かつクーロン効率が９９％を下回ったときを短絡発生と判断した。上記の「クーロン効率」は、そのサイクルでの充電電気量に対する放電容量の百分率である。 (Measurement of number of cycles until internal short circuit occurs)
The charge-discharge cycle life test was performed on the non-aqueous electrolyte storage elements of Examples 1 and 2 and Comparative Examples 1 to 4 until an internal short circuit occurred, and the number of cycles until an internal short circuit occurred was measured. did. The presence or absence of short-circuiting was confirmed by the decrease in coulombic efficiency due to the increase in the amount of charged electricity during the charging/discharging cycle. Specifically, it was determined that a short circuit occurred when the amount of charged electricity increased compared to the amount of charged electricity in the immediately preceding cycle and the coulombic efficiency fell below 99%. The "coulombic efficiency" mentioned above is the percentage of the discharge capacity to the charge charge in that cycle.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　上記表１に示されるように、正極合剤ペーストにホスホン酸を混合し、かつ非水電解質にＬｉＤＦＰを添加した実施例１は、比較例１から３に比べ、内部抵抗の増加率が低減され、しかも短絡発生までのサイクル数が増加した。同様に、正極合剤ペーストにホスホン酸を混合し、かつ非水電解質にＬｉＤＦＯＢ（シグマアルドリッチ製）を添加した実施例２は、比較例２から４に比べ、内部抵抗の増加率が低減され、しかも短絡発生までのサイクル数が増加した。すなわち、負極にリチウム金属を用いる場合、正極合剤がリン元素を含み、非水電解質が酸素元素と、フッ素元素と、リン元素及びホウ素元素のうち少なくとも一方とを含む化合物ａを含むことにより、内部抵抗の増加率が低減され、かつ短絡発生までのサイクル数が増加するという優れた効果が得られることがわかる。 As shown in Table 1 above, in Example 1 in which phosphonic acid was mixed in the positive electrode mixture paste and LiDFP was added to the non-aqueous electrolyte, the rate of increase in internal resistance was reduced compared to Comparative Examples 1 to 3. Moreover, the number of cycles until the occurrence of a short circuit increased. Similarly, in Example 2 in which phosphonic acid was mixed in the positive electrode mixture paste and LiDFOB (manufactured by Sigma-Aldrich) was added to the non-aqueous electrolyte, the rate of increase in internal resistance was reduced compared to Comparative Examples 2 to 4. Moreover, the number of cycles until the occurrence of a short circuit increased. That is, when lithium metal is used for the negative electrode, the positive electrode mixture contains a phosphorus element, and the non-aqueous electrolyte contains a compound a containing an oxygen element, a fluorine element, and at least one of the phosphorus element and the boron element, It can be seen that the rate of increase in internal resistance is reduced and the number of cycles until the occurrence of a short circuit is increased.
　一方、上記表１の参考例１は、正極合剤ペーストにホスホン酸を混合し、かつ非水電解質にＬｉＤＦＰを添加したが、参考例２から４に比べ内部抵抗の増加率は低減されなかった。このことから、上記効果は負極にリチウム金属を用いる場合に特有の効果であり、負極に黒鉛を用いる場合には上記効果を得られないことがわかる。この理由としては、負極に黒鉛を用いた場合、負極にリチウム金属を用いた場合のようにＬｉＤＦＰが負極表面で選択的に反応せず、正極においてホスホン酸由来の被膜及びＬｉＤＦＰ由来の被膜の両方が形成されることにより、正極の電子伝導性の低下及び電荷移動抵抗の増加を招くことが推測される。その結果、内部抵抗が大きく増大すると考えられる。なお、表１には示さないが、参考例１から４は、実施例１、２及び比較例１から４よりも遥かにエネルギー密度が小さかった。 On the other hand, in Reference Example 1 in Table 1 above, phosphonic acid was mixed in the positive electrode mixture paste and LiDFP was added to the non-aqueous electrolyte, but the rate of increase in internal resistance was not reduced compared to Reference Examples 2 to 4. . From this, it can be seen that the above effect is peculiar to the case where lithium metal is used for the negative electrode, and that the above effect cannot be obtained when graphite is used for the negative electrode. The reason for this is that when graphite is used for the negative electrode, LiDFP does not react selectively on the negative electrode surface as in the case where lithium metal is used for the negative electrode, and both the phosphonic acid-derived coating and the LiDFP-derived coating are formed on the positive electrode. It is speculated that the formation of will lead to a decrease in the electronic conductivity of the positive electrode and an increase in the charge transfer resistance. As a result, it is considered that the internal resistance increases greatly. Although not shown in Table 1, Reference Examples 1 to 4 had much smaller energy densities than Examples 1 and 2 and Comparative Examples 1 to 4.
　上述の通り、当該非水電解質蓄電素子は、エネルギー密度が高く、充放電サイクルに伴う内部抵抗の増加を抑制することができ、かつ内部短絡の発生を遅延させることが可能であることが示された。 As described above, it has been shown that the non-aqueous electrolyte storage element has a high energy density, can suppress an increase in internal resistance due to charge-discharge cycles, and can delay the occurrence of an internal short circuit. rice field.
　本発明は、パーソナルコンピュータ、通信端末等の電子機器、自動車などの電源として使用される非水電解質蓄電素子及び蓄電装置などに適用できる。 The present invention can be applied to electronic devices such as personal computers, communication terminals, non-aqueous electrolyte storage elements and storage devices used as power sources for automobiles and the like.
１　　非水電解質蓄電素子
２　　電極体
３　　容器
４　　正極端子
４１　正極リード
５　　負極端子
５１　負極リード
２０　蓄電ユニット
３０　蓄電装置 1 Non-aqueous electrolyte storage element 2 Electrode body 3 Container 4 Positive electrode terminal 41 Positive electrode lead 5 Negative electrode terminal 51 Negative electrode lead 20 Storage unit 30 Storage device

Claims (4)

  1. 　リン元素を含む正極合剤を有する正極と、
    　リチウム金属を含む負極と、
    　化合物ａを含む非水電解質と
    　を備え、
    　上記化合物ａが酸素元素と、フッ素元素と、リン元素及びホウ素元素のうち少なくとも一方とを含む非水電解質蓄電素子。     a positive electrode having a positive electrode mixture containing a phosphorus element;
    a negative electrode comprising lithium metal;
    and a non-aqueous electrolyte containing compound a;
    A non-aqueous electrolyte power storage device in which the compound a contains oxygen element, fluorine element, and at least one of phosphorus element and boron element.
  2. 　上記化合物ａが、ジフルオロリン酸リチウム（ＬｉＤＦＰ）又はリチウムジフルオロオキサレートボレート（ＬｉＤＦＯＢ）である請求項１に記載の非水電解質蓄電素子。 The non-aqueous electrolyte storage element according to claim 1, wherein the compound a is lithium difluorophosphate (LiDFP) or lithium difluorooxalate borate (LiDFOB).
  3. 　エックス線光電子分光法による上記正極合剤のスペクトルにおいて、Ｐ２ｐのピーク位置が１３５ｅＶ以下である請求項１又は請求項２に記載の非水電解質蓄電素子。 3. The non-aqueous electrolyte storage element according to claim 1, wherein the P2p peak position is 135 eV or less in the spectrum of the positive electrode mixture obtained by X-ray photoelectron spectroscopy.
  4. 　非水電解質蓄電素子を二以上備え、且つ請求項１から請求項３のいずれか1項に記載の非水電解質蓄電素子を一以上備えた蓄電装置。 A power storage device comprising two or more non-aqueous electrolyte power storage elements and one or more non-aqueous electrolyte power storage elements according to any one of claims 1 to 3.
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