WO2012014852A1 - Active-material electrolyte composite, process for producing same, and all-solid-state lithium-sulfur secondary battery - Google Patents

Active-material electrolyte composite, process for producing same, and all-solid-state lithium-sulfur secondary battery Download PDF

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WO2012014852A1
WO2012014852A1 PCT/JP2011/066876 JP2011066876W WO2012014852A1 WO 2012014852 A1 WO2012014852 A1 WO 2012014852A1 JP 2011066876 W JP2011066876 W JP 2011066876W WO 2012014852 A1 WO2012014852 A1 WO 2012014852A1
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electrolyte
active material
lithium
electrode
secondary battery
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PCT/JP2011/066876
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French (fr)
Japanese (ja)
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尚希 塚原
村上　裕彦
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株式会社アルバック
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Priority to JP2012526494A priority Critical patent/JP5560337B2/en
Publication of WO2012014852A1 publication Critical patent/WO2012014852A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/581—Chalcogenides or intercalation compounds thereof
    • 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
    • H01M10/36—Accumulators not provided for in groups H01M10/05-H01M10/34
    • H01M10/39—Accumulators not provided for in groups H01M10/05-H01M10/34 working at high temperature
    • 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
    • H01M10/36—Accumulators not provided for in groups H01M10/05-H01M10/34
    • H01M10/39—Accumulators not provided for in groups H01M10/05-H01M10/34 working at high temperature
    • H01M10/3909—Sodium-sulfur cells
    • H01M10/3918—Sodium-sulfur cells characterised by the electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/581—Chalcogenides or intercalation compounds thereof
    • H01M4/5815—Sulfides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to an active material-electrolyte complex, a method for producing the same, and an all-solid-state lithium-sulfur secondary battery, and in particular, contacts between electrode active material particles and an electrolyte having a gelled electrolyte using an ether organic solvent.
  • Active material-electrolyte composite maintaining its safety, its manufacturing method, and using this active material-electrolyte composite, the safety is improved while maintaining the contact between the electrode active material particles and the electrolyte, and it is a discharge product.
  • the present invention relates to an all solid-state lithium-sulfur secondary battery in which elution of lithium polysulfide and low lithium sulfide into an electrolyte is suppressed.
  • Lithium ion secondary batteries have characteristics such as high energy density and high output as compared with other types of batteries, and are often used as batteries for mobile phones, notebook computers and the like.
  • active research has been conducted with the aim of spreading to hybrid vehicles and electric vehicles, and with the research on hybrid vehicles and electric vehicles, further increase in capacity of lithium ion secondary batteries is required.
  • a lithium-sulfur secondary battery using single sulfur which is said to be high capacity, low cost, and environmentally friendly, as a positive electrode active material has attracted attention.
  • the theoretical capacity of elemental sulfur is 1675 mAh / g, which is larger than the capacity of a positive electrode active material (for example, LiCoO 2 : about 140 mAh / g) used in a general lithium ion secondary battery. It is known that
  • lithium sulfide Li 2 S
  • Li 2 S lithium sulfide
  • an electrode mixture containing an electrode active material in order to increase the mechanical strength of the electrode mixture and improve the impregnation property of the electrolytic solution, a clay mineral such as smectite is 5 based on the total weight of the electrode mixture.
  • An electrode mixture contained in a range of not more than% by weight is known (for example, see Patent Document 2).
  • the clay mineral is contained in the electrode mixture, and is used as a slurry to improve the wettability of the electrolytic solution in addition to improving the mechanical strength and impregnating the electrolytic solution.
  • a solid electrolyte composed of a mixture of an electrolytic solution in which an electrolyte is dissolved in an organic compound, a polymer material that forms a gel by mixing with the electrolytic solution, and layered clay compound particles that exhibit swelling properties.
  • a polymer material such as polyvinylidene fluoride (PVdF) is used to form a gel.
  • lithium ion secondary batteries using organic electrolytes, it is safe to say that there are ignition phenomena caused by short circuits caused by liquid leakage from batteries and precipitation of dendritic lithium (dendrites) from negative electrodes due to repeated use of batteries. It is pointed out from the aspect. Considering that lithium ion secondary batteries are used in various applications, it is necessary to give more importance to suppression of liquid leakage and safety. Therefore, there is an urgent need to develop a lithium-ion secondary battery with improved leakage control and safety, such as studying the structure of the battery itself, developing a non-burning electrolyte, and developing an inorganic solid electrolyte. .
  • An object of the present invention is to solve the above-mentioned problems of the prior art, using a gelled electrolyte capable of preventing leakage of an electrolytic solution, and maintaining the contact between the particles of the electrode active material and the electrolyte It is an object of the present invention to provide an all-solid-state lithium-sulfur secondary battery that has high safety and that can improve cycle characteristics.
  • a swellable layered clay mineral such as scumite
  • the active material-electrolyte composite of the present invention is an electrode material in which an active material, a conductive additive, and a binder are mixed at a predetermined ratio, and the positive electrode active material is elemental sulfur or lithium-containing sulfide.
  • a gelled electrolyte made of a mixture of a lithium ion conductive electrolyte and a swellable lamellar clay mineral containing an ether organic solvent is provided on an electrode provided on a current collector, and the gel is applied to the electrode. It is characterized in that it is vibrated with such a strength that the electrolytic electrolyte is liquefied.
  • the swellable layered clay mineral is a smectite-based layered clay mineral or a mica-based layered clay mineral.
  • the lithium-containing sulfide is lithium sulfide (Li 2 S).
  • the method for producing an active material-electrolyte composite of the present invention is an electrode material in which an active material, a conductive additive, and a binder are mixed at a predetermined ratio, and the positive electrode active material is composed of elemental sulfur or lithium-containing sulfide.
  • a gelled electrolyte composed of a mixture of a lithium ion conductive electrolyte and a swellable layered clay mineral containing an ether organic solvent is applied to an electrode provided with a certain electrode material on a current collector, and then gelled.
  • the electrode to which the electrolyte is applied is vibrated at such a strength that the gelled electrolyte liquefies, and the gelled electrolyte is liquefied and penetrated into the electrode to produce an active material-electrolyte complex.
  • the swellable layered clay mineral is a smectite-based layered clay mineral or a mica-based layered clay mineral.
  • the lithium-containing sulfide is lithium sulfide (Li 2 S).
  • the all solid-state lithium-sulfur secondary battery of the present invention is characterized by using the above active material-electrolyte complex.
  • the active material-electrolyte complex is a positive electrode active material-electrolyte complex.
  • the active material-electrolyte complex is a negative electrode active material-electrolyte complex.
  • the active material-electrolyte complex is a positive electrode active material-electrolyte complex and a negative electrode active material-electrolyte complex.
  • the present invention by using a gelled electrolyte obtained by gelling an electrolytic solution using an ether organic solvent, leakage of the electrolytic solution is suppressed and the contact between the electrode active material particles and the electrolyte is maintained. As a result, it is possible to provide an all-solid-state lithium-sulfur secondary battery in which safety is improved and elution of lithium polysulfide and low-sulfide lithium as discharge products into the electrolyte can be provided.
  • FIG. 1 is a schematic diagram for explaining the state of an electrode using an active material-electrolyte complex of the present invention, wherein (a) is a case where vibration is produced according to the present invention, and (b) is a comparative example. Therefore, when it is manufactured without giving vibration.
  • 6 is a graph showing charge / discharge curves of lithium-sulfur secondary batteries produced in Example 3 and Comparative Example 2.
  • 3 is a graph showing discharge capacity curves obtained with respective repetitive cycle characteristics of lithium-sulfur secondary batteries produced in Example 3 and Comparative Example 2.
  • FIG. 6 is a graph showing a charge / discharge curve of a lithium-sulfur secondary battery produced in Comparative Example 3.
  • the active material-electrolyte complex is an electrode material in which an active material, a conductive additive, and a binder are mixed at a predetermined ratio.
  • a lithium ion conductive electrolysis comprising an ether organic solvent on an electrode provided with an electrode material on which a positive electrode active material is elemental sulfur or lithium-containing sulfide (for example, lithium sulfide: Li 2 S) on a current collector
  • a gelled electrolyte comprising a mixture of a liquid and a predetermined amount of a swellable layered clay mineral selected from a smectite-based layered clay mineral and a mica-based layered clay mineral is provided, and the gelled electrolyte is liquefied with respect to this electrode.
  • the vibration method is not particularly limited as long as the gelled electrolyte is liquefied.
  • the vibration is carried by holding it in the hand or by applying vibrations such as ultrasonic waves, the gelled electrolyte is liquefied and penetrates into the electrode, thereby covering all the active materials.
  • This active material-electrolyte complex can be used for both the positive electrode and the negative electrode.
  • the active material examples include known positive electrode active materials selected from lithium-containing sulfides such as elemental sulfur (S) and lithium sulfide (Li 2 S), carbon-based materials such as carbon and carbon black, silicon-based materials, A known negative electrode active material selected from a tin-based material, a silicon-carbon-based material, lithium titanium oxide (for example, Li 4 Ti 5 O 12 ), Li metal, Li—Al alloy, and the like is included.
  • known positive electrode active materials selected from lithium-containing sulfides such as elemental sulfur (S) and lithium sulfide (Li 2 S), carbon-based materials such as carbon and carbon black, silicon-based materials
  • any material can be used as long as it does not cause a chemical change in the target lithium-sulfur secondary battery and has conductivity, and is not particularly limited.
  • graphite various carbon blacks, conductive fibers, metal powders such as copper powder and iron powder, and the like can be used.
  • the binder is not particularly limited as long as it is a substance that does not cause a chemical change in the target lithium-sulfur secondary battery and has a function as a binder.
  • PVdF polyvinylidene fluoride
  • polyethylene polyethylene
  • polypropylene polypropylene
  • polytetrafluoroethylene PTFE
  • any material can be used as long as it does not cause a chemical change in the target lithium-sulfur secondary battery and has conductivity, and is not particularly limited.
  • a positive electrode current collector selected from stainless steel, aluminum, nickel, titanium and the like, and a negative electrode current collector selected from copper, stainless steel, aluminum, nickel, titanium and the like can be used.
  • the gelled electrolyte used in the present invention contains an ether organic solvent, a lithium ion conductive electrolyte and a smectite layered clay mineral, or a predetermined amount of a swellable layered layer selected from a mica layered clay mineral. It consists of a mixture with clay minerals.
  • the gelled electrolyte is obtained by adding a swellable lamellar clay mineral in an organic solvent and sufficiently swelling the clay mineral, and adding it to the electrolyte solution as described below, or It is preferable to prepare it by mixing with an electrolyte, but it is not limited to such a method, and the order of addition is not limited as long as the gelled electrolyte of the present invention can be prepared.
  • ether organic solvent known solvents used in lithium ion secondary batteries can be used and are not particularly limited.
  • 1,3-dioxolane (DOL), tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, diethyl ether, 1,2-diethoxyethane, triethylene glycol dimethyl ether, etc. should be used. Can do. Also, two or more of these ether organic solvents can be mixed and used.
  • lithium salt added to the organic solvent of the electrolytic solution those commonly used can be used.
  • an electrolyte selected from LiClO 4 , LiPF 6 , LiAsF 6 , LiN (CF 3 SO 2 ) 2 , LiBF 4 , LiCF 3 SO 3 , LiSbF 6 and the like in an organic solvent can be used.
  • the smectite layered clay mineral can be used as long as it exhibits thixotropic properties, and is not particularly limited.
  • Product name: Lucentite STN can be used, and hectorite, bentonite, montmorillonite, synthetic smectite (manufactured by Coop Chemical Co., Ltd., product name: Lucentite STN) and the like are preferable.
  • the mica-based layered clay mineral can be used as long as it exhibits thixotropic properties, and is not particularly limited.
  • mica, brittle mica, muscovite, soda mica, phlogopite, biotite, etc. can be used, and mica is preferred.
  • the swellable layered clay mineral used in the present invention exhibits thixotropic properties when added to a solvent.
  • the thixotropy is a phenomenon in which the viscosity gradually decreases and becomes liquid when it continues to receive shear stress (vibration), and the viscosity gradually increases when it is stationary, and finally becomes solid.
  • the gelled electrolyte is first liquefied, and the gelled electrolyte is spread over the entire electrode so as to sufficiently cover the periphery of the active material, and only the electrolyte is used.
  • the present invention provides an electrode surface while applying physical vibrations such as ultrasonic waves to an electrode in which an electrode material containing an electrode active material is provided on a current collector (for example, Al foil, Cu foil, etc.).
  • a current collector for example, Al foil, Cu foil, etc.
  • the mixing ratio of the lithium ion conductive electrolyte and the swellable layered clay mineral may be appropriately blended in such an amount that the electrolyte can exhibit thixotropy.
  • the amount of the swellable layered clay mineral increases, it becomes solid, so that thixotropy is not expressed, and as the amount of the swellable layered clay mineral decreases, the liquid becomes closer to the liquid.
  • the amount of the swellable layered clay mineral added is preferably in the range of about 2 wt% to 10 wt% based on the total weight of the mixture.
  • the thixotropic property tends not to be expressed, and if it exceeds 10 wt%, gelation tends to proceed as compared with 10 wt%, and the thixotropic property is not expressed.
  • this production method comprises a predetermined ratio (for example, a weight ratio of 45) of the active material, the conductive additive, and the binder. : 45: 10)
  • the gelled electrolyte is applied to the electrode obtained by coating the electrode material mixed on the current collector, and then the gelled electrolyte is applied to the electrode coated with the gelled electrolyte.
  • the above-mentioned vibration preferably ultrasonic vibration
  • the liquefied gelled electrolyte is uniformly infiltrated into the electrode, and the active material is covered with the electrolyte. It is.
  • the active material, the conductive auxiliary material, and the binder are blended as follows, for example.
  • the conductive additive is mixed in an amount of 1 to 50 wt%, preferably 30 to 50 wt%, based on the total weight of the positive electrode. If it is less than 1 wt%, sufficient conductivity cannot be exhibited, and if it exceeds 50 wt%, the amount of the positive electrode active material is reduced, resulting in a problem that the capacity is reduced.
  • the binder is mixed in an amount of 1 to 50 wt%, preferably 5 to 30 wt% based on the total weight of the positive electrode. If it is less than 1 wt%, the binding ability is lowered, and if it exceeds 50 wt%, the amount of the positive electrode active material is reduced, resulting in a problem that the capacity is reduced.
  • the secondary battery uses the gelled electrolyte, and the gelled electrolyte is placed in the positive electrode material on the current collector. It is impregnated and used as a positive electrode composite and / or this gelled electrolyte is infiltrated into a negative electrode material on a current collector and used as a negative electrode composite.
  • the gelled electrolyte of the present invention When the gelled electrolyte of the present invention is used, the electrolyte liquefied by vibration automatically penetrates into the positive electrode (negative electrode) material applied to the Al foil (positive electrode) or Cu foil (negative electrode) as the current collector.
  • a separator that is usually used to prevent a short circuit between the positive electrode and the negative electrode may or may not be used.
  • any ordinary known separator may be used.
  • a porous polypropylene film manufactured by Celgard; trade name: Celgard # 2400
  • Celgard # 2400 can be used.
  • an electrode material in which an active material 11, a binder 12, and a conductive additive 13 are mixed at a predetermined ratio is applied on a current collector 14, and the electrode is formed.
  • An active material is obtained by applying an organic solvent-containing gelled electrolyte 15 containing a lithium ion conductive electrolyte and a swellable layered clay mineral to the electrode, and applying vibration (for example, ultrasonic vibration).
  • vibration for example, ultrasonic vibration
  • -An electrolyte composite electrolyte composite
  • a lithium-sulfur secondary battery can be assembled by a known method using the active material-electrolyte composite thus prepared as an electrode.
  • DME 1,2-dimethoxyethane
  • the ultrasonic vibration was given to the gelled electrolyte produced in Example 1. While applying vibration, it was confirmed that the gelled electrolyte was liquefied, stopped vibrating, and then allowed to stand to gel (solidify).
  • the gelled electrolyte produced in Example 1 was applied on the surface of the positive electrode, and ultrasonic vibration was applied to liquefy the gelled electrolyte, so that it penetrated into the positive electrode as shown in FIG. A substance-electrolyte complex was prepared. As a result, as shown in FIG.
  • a 2032 type lithium-sulfur secondary battery was assembled using the positive electrode composite thus produced as a positive electrode and Li metal as a negative electrode, and a charge / discharge test was performed.
  • the charge / discharge current value was 192.74 ⁇ A / cm 2 (corresponding to a 0.1 C rate)
  • the cut-off voltage was 1.5-2.8 V
  • charge / discharge was repeated 43 cycles. Since elemental sulfur was used as the positive electrode, measurement was started from the discharge reaction.
  • Example 1 A lithium-sulfur secondary battery was assembled according to the method described in Example 3 except that no ultrasonic vibration was applied, and a charge / discharge test was performed. In this case, the charge / discharge current value was 190 ⁇ A / cm 2 (corresponding to a 0.1 C rate).
  • a lithium-sulfur secondary battery was assembled according to the method described in Example 3 except that a porous polypropylene film (manufactured by Celgard; trade name: Celgard # 2400) was used as the separator, and a charge / discharge test was performed. In this case, the charge / discharge current value was 189.75 ⁇ A / cm 2 (corresponding to a 0.1 C rate), and charge / discharge was repeated 45 cycles. Since elemental sulfur was used as the positive electrode, measurement was started from the discharge reaction.
  • a porous polypropylene film manufactured by Celgard; trade name: Celgard # 2400
  • the charge / discharge curves of the first cycle of the lithium-sulfur secondary batteries produced in Example 3 and Comparative Example 2 are shown in FIG.
  • the vertical axis represents E / V (Li / Li + ), and the horizontal axis represents discharge capacity (mAh / g (active material)).
  • the initial discharge capacity is 1000 mAh / g, indicating that a high discharge capacity is obtained.
  • FIG. 3 shows the discharge capacities obtained with the respective repetitive cycle characteristics of the lithium-sulfur secondary batteries produced in Example 3 and Comparative Example 2.
  • the vertical axis represents the discharge capacity (mAh / g (active material)), and the horizontal axis represents the number of cycles.
  • the discharge capacity of Example 3 is greater than the discharge capacity of Comparative Example 2 after 20 cycles, and the cycle characteristics are improved.
  • the charge / discharge current value was 355.08 ⁇ A / cm 2 (corresponding to a 0.1 C rate)
  • the cut-off voltage was 1.4-3.0 V
  • charge / discharge was repeated three cycles. Since elemental sulfur was used as the positive electrode, measurement was started from the discharge reaction.
  • FIG. 4 shows charge / discharge curves of the lithium-sulfur secondary battery manufactured in Comparative Example 3 for the first cycle (1st), the second cycle (2nd), and the third cycle (3rd).
  • the vertical axis represents E / V (Li / Li + ), and the horizontal axis represents discharge capacity (mAh / g (active material)).
  • a carbonate-based organic solvent when used, discharging is possible but charging is not possible.
  • 1,2-dimethoxyethane used in Example 1, 1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethyl ether, 1,2-diethoxy were used as ether organic solvents.
  • a gelled electrolyte was prepared using ethane and triethylene glycol dimethyl ether, respectively, and a lithium-sulfur secondary battery was prepared according to the method described in Example 3. As a result, a charge / discharge curve similar to the results shown in FIGS. And discharge capacity was found to be obtained.
  • a lithium-sulfur secondary battery was produced according to the method described in Example 3 except that Li 2 S was used instead of sulfur, which is the positive electrode active material used in Example 3, and the results shown in FIGS. It was found that the same charge / discharge curve and discharge capacity as those obtained were obtained.
  • Example 2 the amount of the synthetic smectite used in Example 1 was changed, and an electrolyte was prepared according to the method described in Example 1 in the following proportions (1) to (7). According to Example 2, ultrasonic vibration was applied and the state was observed.
  • the following synthetic smectite addition amount is a ratio with respect to the obtained electrolyte weight.
  • Synthetic smectite 50 mg + DEC: 2 g + electrolytic solution: 567 mg (addition amount of synthetic smectite: 1.91 wt%) (2) Synthetic smectite: 100 mg + DEC: 2 g + electrolytic solution: 567 mg (additional amount of synthetic smectite: 3.75 wt%) (3) Synthetic smectite: 150 mg + DEC: 2 g + Electrolytic solution: 567 mg (Additional amount of synthetic smectite: 5.52 wt%) (4) Synthetic smectite 200 mg + DEC: 2 g + electrolytic solution: 567 mg (synthetic smectite addition amount: 7.23 wt%) (5) Synthetic smectite 300 mg + DEC: 2 g + electrolytic solution: 567 mg (synthetic smectite addition amount: 10.5 wt%) (6) Synthetic smectit
  • (1) is in a liquid state and no thixotropic property is observed
  • (2) has thixotropic properties
  • (3) has thixotropic properties.
  • (4) is more gelled than (3) but has thixotropic properties
  • (5) is more gelled than (4) and is almost solid
  • thixotropic properties are No (6) was almost solid and no thixotropic property was seen, and (7) was almost solid and no thixotropic property was seen.
  • the amount of the swellable layered clay mineral is preferably in the range of about 2 wt% to 10 wt%.
  • a lithium-sulfur secondary battery was produced according to the method described in Example 3 except that hectorite, bentonite and montmorillonite were used instead of the synthetic smectite used in Example 1, and the results are shown in FIGS. It was found that the same charge / discharge curve and discharge capacity as the results were obtained.
  • the lithium-sulfur secondary battery is used. It can be used in various industries.

Abstract

Disclosed is an active-material electrolyte composite prepared by: providing a gelled electrolyte on an electrode, the electrode including a charge collector and an electrode material provided thereon, the electrode material being prepared by mixing an active material, an electroconductive aid, and a binder at a predetermined mixing ratio and containing elemental sulfur or a lithium-containing sulfide as a positive-electrode active material, the gelled electrolyte containing an ether-based organic solvent and comprising a mixture of a lithium-ion-conductive electrolytic solution and a swellable layered clay mineral; and subjecting the electrode to a vibration having an intensity that will liquefy the gelled electrolyte. Also disclosed is an all-solid-state lithium-sulfur secondary battery produced by using said composite.

Description

活物質－電解質複合体及びその作製方法、並びに全固体型リチウム－硫黄二次電池Active material-electrolyte composite, method for producing the same, and all solid-state lithium-sulfur secondary battery
　本発明は、活物質－電解質複合体及びその作製方法、並びに全固体型リチウム－硫黄二次電池に関し、特にエーテル系有機溶媒を用いたゲル化電解質を有する、電極活物質粒子と電解質との接触性を維持した活物質－電解質複合体及びその作製方法、並びにこの活物質－電解質複合体を用い、電極活物質粒子と電解質との接触性を維持したまま安全性を高め、放電生成物である多硫化リチウム及び低硫化リチウムの電解質中への溶出を抑制した全固体型リチウム－硫黄二次電池に関する。 The present invention relates to an active material-electrolyte complex, a method for producing the same, and an all-solid-state lithium-sulfur secondary battery, and in particular, contacts between electrode active material particles and an electrolyte having a gelled electrolyte using an ether organic solvent. Active material-electrolyte composite maintaining its safety, its manufacturing method, and using this active material-electrolyte composite, the safety is improved while maintaining the contact between the electrode active material particles and the electrolyte, and it is a discharge product. The present invention relates to an all solid-state lithium-sulfur secondary battery in which elution of lithium polysulfide and low lithium sulfide into an electrolyte is suppressed.
　リチウムイオン二次電池は、他のタイプの電池と比べて高エネルギー密度、高出力といった特徴を持っており、携帯電話やノートパソコン等のバッテリーとして多く用いられている。また、近年、ハイブリット車や電気自動車への普及を目指し、盛んに研究が行われており、そのハイブリット車や電気自動車の研究に伴い、リチウムイオン二次電池のさらなる高容量化が求められている。そのような状況の下、高容量・低コスト・環境にやさしいと言われている単体硫黄を正極活物質に用いたリチウム－硫黄二次電池が注目されている。単体硫黄の理論容量は、１６７５ｍＡｈ／ｇであり、一般的なリチウムイオン二次電池で使用されている正極活物質の容量（例えば、ＬｉＣｏＯ２：約１４０ｍＡｈ／ｇ）と比べて大きな容量を持っていることが知られている。 Lithium ion secondary batteries have characteristics such as high energy density and high output as compared with other types of batteries, and are often used as batteries for mobile phones, notebook computers and the like. In recent years, active research has been conducted with the aim of spreading to hybrid vehicles and electric vehicles, and with the research on hybrid vehicles and electric vehicles, further increase in capacity of lithium ion secondary batteries is required. . Under such circumstances, a lithium-sulfur secondary battery using single sulfur, which is said to be high capacity, low cost, and environmentally friendly, as a positive electrode active material has attracted attention. The theoretical capacity of elemental sulfur is 1675 mAh / g, which is larger than the capacity of a positive electrode active material (for example, LiCoO 2 : about 140 mAh / g) used in a general lithium ion secondary battery. It is known that
　しかし、通常の有機系電解液を用いたリチウムイオン二次電池の正極活物質に単体硫黄を用いる場合、（１）単体硫黄（Ｓ）は絶縁体であるので、電極として使用するためには多量の導電助材が必要になり、（２）二次電池での放電反応により生じる中間生成物の多硫化リチウム（Ｌｉ２Ｓｘ：ｘ＝２～８）が電解液に可溶であることから、正極活物質の利用効率が悪くなり、また、溶解した多硫化リチウムが負極のＬｉ金属と反応して自己放電を起こすことで充放電サイクル特性が悪くなり、（３）過放電により生成する低硫化リチウム（Ｌｉ２Ｓ）は絶縁・不溶性であることから、正極上に堆積してしまい、それが不可逆容量の要因となることで、サイクル特性が悪くなるといった問題があった。さらに有機電解液を用いていることから、電解液の漏洩・発火が起こる可能性があり、安全性にも問題があった。 However, when elemental sulfur is used as the positive electrode active material of a lithium ion secondary battery using an ordinary organic electrolyte, (1) elemental sulfur (S) is an insulator, so that it is a large amount for use as an electrode. (2) The intermediate product lithium polysulfide (Li 2 S x : x = 2 to 8) generated by the discharge reaction in the secondary battery is soluble in the electrolyte. In addition, the utilization efficiency of the positive electrode active material is deteriorated, and the dissolved lithium polysulfide reacts with Li metal of the negative electrode to cause self-discharge, resulting in poor charge / discharge cycle characteristics, and (3) low generation due to overdischarge. Since lithium sulfide (Li 2 S) is insulative and insoluble, it is deposited on the positive electrode, which causes irreversible capacity, resulting in poor cycle characteristics. Furthermore, since the organic electrolyte is used, there is a possibility that the electrolyte will leak and ignite, which causes a problem in safety.
　また、一般的なリチウムイオン電池に使用されているカーボネート系有機溶媒を用いると、多硫化リチウムが溶解しないため、放電は可能であるが、充電ができなくなってしまうと言われている（例えば、特許文献１参照）。 In addition, it is said that when a carbonate organic solvent used in a general lithium ion battery is used, lithium polysulfide is not dissolved, so that discharge is possible but charging is not possible (for example, Patent Document 1).
　また、電極活物質を含む電極合剤として、電極合剤の機械的強度を高めて電解液の含浸性を向上させるために、スメクタイト等の粘土鉱物が電極合剤の全体重量を基準にして５重量％以下の範囲で含まれている電極合剤が知られている（例えば、特許文献２参照）。この場合、粘土鉱物は、電極合剤に含有させて、機械的強度の向上、電解液の含浸性に加えて、電解液の濡れ性を向上させるためにスラリーとして用いられている。 Further, as an electrode mixture containing an electrode active material, in order to increase the mechanical strength of the electrode mixture and improve the impregnation property of the electrolytic solution, a clay mineral such as smectite is 5 based on the total weight of the electrode mixture. An electrode mixture contained in a range of not more than% by weight is known (for example, see Patent Document 2). In this case, the clay mineral is contained in the electrode mixture, and is used as a slurry to improve the wettability of the electrolytic solution in addition to improving the mechanical strength and impregnating the electrolytic solution.
　さらに、電解質を有機化合物に溶解した電解液と、該電解液との混合によりゲルを形成する高分子材料と、膨潤性を示す層状粘土化合物粒子との混合体からなる固体状電解質が知られている（例えば、特許文献３参照）。この技術では、ゲルを形成するために、ポリフッ化ビニリデン（ＰＶｄＦ）等の高分子材料を使用している。 Furthermore, there is known a solid electrolyte composed of a mixture of an electrolytic solution in which an electrolyte is dissolved in an organic compound, a polymer material that forms a gel by mixing with the electrolytic solution, and layered clay compound particles that exhibit swelling properties. (For example, see Patent Document 3). In this technique, a polymer material such as polyvinylidene fluoride (PVdF) is used to form a gel.
　さらにまた、有機系電解液を用いたリチウムイオン二次電池では、電池からの液漏れや電池の繰り返し使用による負極からの樹枝状リチウム（デンドライト）の析出によって生じる短絡による発火現象といったことが、安全面から指摘されている。リチウムイオン二次電池が種々の用途に用いられることを考慮すると、液漏れの抑制や安全性等をさらに重視しなくてはならない。そのため、電池自体の構造の検討、燃えない電解液の開発、無機固体電解質の開発などのような、液漏れの抑制や安全性等を高めたリチウムイオン二次電池の開発が急務となっている。 Furthermore, in lithium ion secondary batteries using organic electrolytes, it is safe to say that there are ignition phenomena caused by short circuits caused by liquid leakage from batteries and precipitation of dendritic lithium (dendrites) from negative electrodes due to repeated use of batteries. It is pointed out from the aspect. Considering that lithium ion secondary batteries are used in various applications, it is necessary to give more importance to suppression of liquid leakage and safety. Therefore, there is an urgent need to develop a lithium-ion secondary battery with improved leakage control and safety, such as studying the structure of the battery itself, developing a non-burning electrolyte, and developing an inorganic solid electrolyte. .
特開２００６－３２１４３号公報JP 2006-32143 A 特開２００８－７１７５７号公報JP 2008-71757 A 特開平１０－２６９８４４号公報Japanese Patent Laid-Open No. 10-269844
　本発明の課題は、上述の従来技術の問題点を解決することにあり、電解液の漏洩を防止することができるゲル化電解質を用い、かつ電極活物質の粒子と電解質との接触性を維持した活物質－電解質複合体及びその作製方法、並びにこの複合体を用いた安全性が高く、サイクル特性の向上が可能な全固体型リチウム－硫黄二次電池を提供することにある。 An object of the present invention is to solve the above-mentioned problems of the prior art, using a gelled electrolyte capable of preventing leakage of an electrolytic solution, and maintaining the contact between the particles of the electrode active material and the electrolyte It is an object of the present invention to provide an all-solid-state lithium-sulfur secondary battery that has high safety and that can improve cycle characteristics.
　上記課題に鑑み、本発明者らは、エーテル系有機溶媒を用いた電解液にスクメタイトのような膨潤性層状粘土鉱物を添加することで電解液のゲル化（固体化）についての検討を行い、ゲル化電解質を用いて活物質－電解質複合体の界面活性を維持しつつ、放電生成物である多硫化リチウム（Ｌｉ２Ｓｘ：ｘ＝２～８）の電解質中への溶出を抑え、放電生成物を正極に保持したまま負極のＬｉ金属との反応を抑制（すなわち、自己放電を抑制）することで充放電サイクル特性の向上を図ることに成功し、本発明を完成させるに至った。 In view of the above problems, the present inventors have examined gelation (solidification) of an electrolyte by adding a swellable layered clay mineral such as scumite to an electrolyte using an ether organic solvent, While maintaining the surface activity of the active material-electrolyte complex using a gelled electrolyte, the discharge of lithium polysulfide (Li 2 S x : x = 2-8), which is a discharge product, is suppressed from elution into the electrolyte By suppressing the reaction of the negative electrode with the Li metal while maintaining the product on the positive electrode (that is, suppressing self-discharge), the inventors succeeded in improving the charge / discharge cycle characteristics and completed the present invention.
　本発明の活物質－電解質複合体は、活物質、導電助材、及び結着材を所定の割合で混合した電極材料であって、正極活物質が単体硫黄又はリチウム含有硫化物である電極材料を集電体上に設けた電極上に、エーテル系有機溶媒を含む、リチウムイオン伝導性電解液と膨潤性層状粘土鉱物との混合物からなるゲル化電解質を設け、この電極に対して、このゲル化電解質が液状化する強さの振動を与えてなることを特徴とする。 The active material-electrolyte composite of the present invention is an electrode material in which an active material, a conductive additive, and a binder are mixed at a predetermined ratio, and the positive electrode active material is elemental sulfur or lithium-containing sulfide. A gelled electrolyte made of a mixture of a lithium ion conductive electrolyte and a swellable lamellar clay mineral containing an ether organic solvent is provided on an electrode provided on a current collector, and the gel is applied to the electrode. It is characterized in that it is vibrated with such a strength that the electrolytic electrolyte is liquefied.
　上記活物質－電解質複合体において、膨潤性層状粘土鉱物は、スメクタイト系層状粘土鉱物、又は雲母系層状粘土鉱物であることを特徴とする。 In the above active material-electrolyte complex, the swellable layered clay mineral is a smectite-based layered clay mineral or a mica-based layered clay mineral.
　上記活物質－電解質複合体において、リチウム含有硫化物が、硫化リチウム（Ｌｉ２Ｓ）であることを特徴とする。 In the above active material-electrolyte complex, the lithium-containing sulfide is lithium sulfide (Li 2 S).
　本発明の活物質－電解質複合体の作製方法は、活物質、導電助材、及び結着材を所定の割合で混合した電極材料であって、正極活物質が単体硫黄又はリチウム含有硫化物である電極材料を集電体上に設けてなる電極上に、エーテル系有機溶媒を含む、リチウムイオン伝導性電解液と膨潤性層状粘土鉱物との混合物からなるゲル化電解質を塗布し、次いでゲル化電解質の塗布された電極に対して、このゲル化電解質が液状化する強さの振動を与え、ゲル化電解質を液状化して電極内へ浸透せしめ活物質－電解質複合体を作製することを特徴とする。 The method for producing an active material-electrolyte composite of the present invention is an electrode material in which an active material, a conductive additive, and a binder are mixed at a predetermined ratio, and the positive electrode active material is composed of elemental sulfur or lithium-containing sulfide. A gelled electrolyte composed of a mixture of a lithium ion conductive electrolyte and a swellable layered clay mineral containing an ether organic solvent is applied to an electrode provided with a certain electrode material on a current collector, and then gelled. This is characterized in that the electrode to which the electrolyte is applied is vibrated at such a strength that the gelled electrolyte liquefies, and the gelled electrolyte is liquefied and penetrated into the electrode to produce an active material-electrolyte complex. To do.
　上記活物質－電解質複合体の作製方法において、膨潤性層状粘土鉱物は、スメクタイト系層状粘土鉱物、又は雲母系層状粘土鉱物であることを特徴とする。 In the above method for producing an active material-electrolyte complex, the swellable layered clay mineral is a smectite-based layered clay mineral or a mica-based layered clay mineral.
　上記活物質－電解質複合体の作製方法において、リチウム含有硫化物が、硫化リチウム（Ｌｉ２Ｓ）であることを特徴とする。 In the above method for producing an active material-electrolyte composite, the lithium-containing sulfide is lithium sulfide (Li 2 S).
　本発明の全固体型リチウム－硫黄二次電池は、上記活物質－電解質複合体を用いたことを特徴とする。 The all solid-state lithium-sulfur secondary battery of the present invention is characterized by using the above active material-electrolyte complex.
　上記全固体型リチウム－硫黄二次電池において、活物質－電解質複合体が正極活物質－電解質複合体であることを特徴とする。 In the all solid-state lithium-sulfur secondary battery, the active material-electrolyte complex is a positive electrode active material-electrolyte complex.
　上記全固体型リチウム－硫黄二次電池において、活物質－電解質複合体が負極活物質－電解質複合体であることを特徴とする。 In the all solid lithium-sulfur secondary battery, the active material-electrolyte complex is a negative electrode active material-electrolyte complex.
　上記全固体型リチウム－硫黄二次電池において、活物質－電解質複合体が、正極活物質－電解質複合体及び負極活物質－電解質複合体であることを特徴とする。 In the all-solid-state lithium-sulfur secondary battery, the active material-electrolyte complex is a positive electrode active material-electrolyte complex and a negative electrode active material-electrolyte complex.
　本発明によれば、エーテル系有機溶媒を用いた電解液をゲル化させてなるゲル化電解質を用いることにより、電解液の漏洩を抑制し、かつ電極活物質粒子と電解質との接触性を維持したまま、安全性を高め、放電生成物である多硫化リチウム及び低硫化リチウムの電解質中への溶出を抑制した全固体型リチウム－硫黄二次電池を提供できるという効果を奏することができる。 According to the present invention, by using a gelled electrolyte obtained by gelling an electrolytic solution using an ether organic solvent, leakage of the electrolytic solution is suppressed and the contact between the electrode active material particles and the electrolyte is maintained. As a result, it is possible to provide an all-solid-state lithium-sulfur secondary battery in which safety is improved and elution of lithium polysulfide and low-sulfide lithium as discharge products into the electrolyte can be provided.
本発明の活物質－電解質複合体を用いた電極の状態を説明するための概略模式図であって、（ａ）は、本発明に従って振動を与えて作製した場合、（ｂ）は、比較のために振動を与えずに作製した場合。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining the state of an electrode using an active material-electrolyte complex of the present invention, wherein (a) is a case where vibration is produced according to the present invention, and (b) is a comparative example. Therefore, when it is manufactured without giving vibration. 実施例３及び比較例２で作製したリチウム－硫黄二次電池のそれぞれの充放電曲線を示すグラフ。6 is a graph showing charge / discharge curves of lithium-sulfur secondary batteries produced in Example 3 and Comparative Example 2. 実施例３及び比較例２で作製したリチウム－硫黄二次電池のそれぞれの繰り返しサイクル特性で得られた放電容量曲線を示すグラフ。3 is a graph showing discharge capacity curves obtained with respective repetitive cycle characteristics of lithium-sulfur secondary batteries produced in Example 3 and Comparative Example 2. FIG. 比較例３で作製したリチウム－硫黄二次電池の充放電曲線を示すグラフ。6 is a graph showing a charge / discharge curve of a lithium-sulfur secondary battery produced in Comparative Example 3.
　以下、本発明の実施の形態について説明する。 Hereinafter, embodiments of the present invention will be described.
　本発明に係る活物質－電解質複合体の実施の形態によれば、この活物質－電解質複合体は、活物質、導電助材、及び結着材を所定の割合で混合した電極材料であって、正極活物質が単体硫黄又はリチウム含有硫化物（例えば、硫化リチウム：Ｌｉ２Ｓ）である電極材料を集電体上に設けた電極上に、エーテル系有機溶媒を含む、リチウムイオン伝導性電解液と、スメクタイト系層状粘土鉱物及び雲母系層状粘土鉱物から選ばれた所定量の膨潤性層状粘土鉱物との混合物からなるゲル化電解質を設け、この電極に対して、ゲル化電解質が液状化する強さの物理的振動を与えてなるものである。ゲル化電解質が液状化する程度の振動であれば、その振動の方法には特に制限はない。例えば、手に持って振動を与え、又は超音波等による振動を与えれば、ゲル化電解質は液状化し、電極内へ浸透し、全ての活物質の周囲を覆うことができる。なお、この活物質－電解質複合体は、正極にも負極にも使用可能である。 According to the embodiment of the active material-electrolyte complex according to the present invention, the active material-electrolyte complex is an electrode material in which an active material, a conductive additive, and a binder are mixed at a predetermined ratio. A lithium ion conductive electrolysis comprising an ether organic solvent on an electrode provided with an electrode material on which a positive electrode active material is elemental sulfur or lithium-containing sulfide (for example, lithium sulfide: Li 2 S) on a current collector A gelled electrolyte comprising a mixture of a liquid and a predetermined amount of a swellable layered clay mineral selected from a smectite-based layered clay mineral and a mica-based layered clay mineral is provided, and the gelled electrolyte is liquefied with respect to this electrode. It gives a physical vibration of strength. The vibration method is not particularly limited as long as the gelled electrolyte is liquefied. For example, if the vibration is carried by holding it in the hand or by applying vibrations such as ultrasonic waves, the gelled electrolyte is liquefied and penetrates into the electrode, thereby covering all the active materials. This active material-electrolyte complex can be used for both the positive electrode and the negative electrode.
　上記活物質には、単体硫黄（Ｓ）、硫化リチウム（Ｌｉ２Ｓ）等のリチウム含有硫化物から選ばれた既知正極活物質、また、カーボンやカーボンブラック等の炭素系物質、シリコン系物質、スズ系物質、シリコン－炭素系物質、リチウムチタン酸化物（例えば、Ｌｉ４Ｔｉ５Ｏ１２等）、Ｌｉ金属、Ｌｉ－Ａｌ合金等から選ばれた既知負極活物質が含まれる。 Examples of the active material include known positive electrode active materials selected from lithium-containing sulfides such as elemental sulfur (S) and lithium sulfide (Li 2 S), carbon-based materials such as carbon and carbon black, silicon-based materials, A known negative electrode active material selected from a tin-based material, a silicon-carbon-based material, lithium titanium oxide (for example, Li 4 Ti 5 O 12 ), Li metal, Li—Al alloy, and the like is included.
　導電助材としては、目的とするリチウム－硫黄二次電池に化学的変化を生じさせず、かつ導電性を有する物質であれば用いることができ、特に制限されない。例えば、黒鉛、各種カーボンブラック、導電性繊維や、銅粉末、鉄粉末等の金属粉末等を用いることができる。 As the conductive aid, any material can be used as long as it does not cause a chemical change in the target lithium-sulfur secondary battery and has conductivity, and is not particularly limited. For example, graphite, various carbon blacks, conductive fibers, metal powders such as copper powder and iron powder, and the like can be used.
　結着材としては、目的とするリチウム－硫黄二次電池に化学的変化を生じさせず、かつ結着材としての作用を有する物質であれば用いることができ、特に制限されない。例えば、ポリフッ化ビニリデン（ＰＶｄＦ）、ポリエチレン、ポリプロピレン、ポリテトラフルオロエチレン（ＰＴＦＥ）等を用いることができる。 The binder is not particularly limited as long as it is a substance that does not cause a chemical change in the target lithium-sulfur secondary battery and has a function as a binder. For example, polyvinylidene fluoride (PVdF), polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or the like can be used.
　集電体としては、目的とするリチウム－硫黄二次電池に化学的変化を生じさせず、かつ導電性を有する物質であれば用いることができ、特に制限されない。例えば、ステンレススチール、アルミニウム、ニッケル、チタン等から選ばれた正極集電体、また、銅、ステンレススチール、アルミニウム、ニッケル、チタン等から選ばれた負極集電体を用いることができる。 As the current collector, any material can be used as long as it does not cause a chemical change in the target lithium-sulfur secondary battery and has conductivity, and is not particularly limited. For example, a positive electrode current collector selected from stainless steel, aluminum, nickel, titanium and the like, and a negative electrode current collector selected from copper, stainless steel, aluminum, nickel, titanium and the like can be used.
　本発明で用いるゲル化電解質は、上記したように、エーテル系有機溶媒を含む、リチウムイオン伝導性電解液とスメクタイト系層状粘土鉱物、又は雲母系層状粘土鉱物から選ばれた所定量の膨潤性層状粘土鉱物との混合物からなるものである。この場合、ゲル化電解質は、有機溶媒中に膨潤性層状粘土鉱物を添加し、この粘土鉱物を充分に膨潤させた上で、これを、以下述べるように、電解液中に添加して、又は電解質と混合して作製するのが好ましいが、このような方法に制限されるわけではなく、本発明のゲル化電解質が作製できれば、その添加順序には制限はない。 As described above, the gelled electrolyte used in the present invention contains an ether organic solvent, a lithium ion conductive electrolyte and a smectite layered clay mineral, or a predetermined amount of a swellable layered layer selected from a mica layered clay mineral. It consists of a mixture with clay minerals. In this case, the gelled electrolyte is obtained by adding a swellable lamellar clay mineral in an organic solvent and sufficiently swelling the clay mineral, and adding it to the electrolyte solution as described below, or It is preferable to prepare it by mixing with an electrolyte, but it is not limited to such a method, and the order of addition is not limited as long as the gelled electrolyte of the present invention can be prepared.
　上記エーテル系有機溶媒としては、リチウムイオン二次電池で用いられている既知の溶媒を用いることができ、特に制限されない。例えば、１，３－ジオキソラン（ＤＯＬ）、テトラヒドロフラン、２－メチルテトラヒドロフラン、１，４－ジオキサン、１，２－ジメトキシエタン、ジエチルエーテル、１，２－ジエトキシエタン、トリエチレングリコールジメチルエーテル等を用いることができる。また、これらのエーテル系有機溶媒の２種以上を混合して用いることもできる。 As the ether organic solvent, known solvents used in lithium ion secondary batteries can be used and are not particularly limited. For example, 1,3-dioxolane (DOL), tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, diethyl ether, 1,2-diethoxyethane, triethylene glycol dimethyl ether, etc. should be used. Can do. Also, two or more of these ether organic solvents can be mixed and used.
　電解液の有機溶媒に加えるリチウム塩としては、一般に使用されているものを用いることができる。例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＡｓＦ６、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＢＦ４、ＬｉＣＦ３ＳＯ３、ＬｉＳｂＦ６等から選ばれた電解質を有機溶媒に溶解したものを用いることができる。 As the lithium salt added to the organic solvent of the electrolytic solution, those commonly used can be used. For example, an electrolyte selected from LiClO 4 , LiPF 6 , LiAsF 6 , LiN (CF 3 SO 2 ) 2 , LiBF 4 , LiCF 3 SO 3 , LiSbF 6 and the like in an organic solvent can be used.
　上記スメクタイト系層状粘土鉱物としては、チキソトロピー性を示すものであれば用いることができ、特に制限されない。例えば、ベントナイト、ラポナイト、ヘクトライト、ギブサイト、クロライト、カオリナイト、ハロイサイト、ピロフィライト、タルク、モンモリロナイト、バーミキュライト、イライト、バイデライト、ノントロナイト、ポルコンスコアイト、及び合成スメクタイト（コープケミカル（株）製、商品名：ルーセンタイトＳＴＮ）等を用いることができ、ヘクトライト、ベントナイト、モンモリロナイト、合成スメクタイト（コープケミカル（株）製、商品名：ルーセンタイトＳＴＮ）等が好ましい。 The smectite layered clay mineral can be used as long as it exhibits thixotropic properties, and is not particularly limited. For example, bentonite, laponite, hectorite, gibbsite, chlorite, kaolinite, halloysite, pyrophyllite, talc, montmorillonite, vermiculite, illite, beidellite, nontronite, polcon score, and synthetic smectite (manufactured by Corp Chemical Co., Ltd.) Product name: Lucentite STN) can be used, and hectorite, bentonite, montmorillonite, synthetic smectite (manufactured by Coop Chemical Co., Ltd., product name: Lucentite STN) and the like are preferable.
　上記雲母系層状粘土鉱物としては、チキソトロピー性を示すものであれば用いることができ、特に制限されない。例えば、マイカ、ブリトルマイカ、白雲母、ソーダ雲母、金雲母、及び黒雲母等を用いることができ、マイカ等が好ましい。 The mica-based layered clay mineral can be used as long as it exhibits thixotropic properties, and is not particularly limited. For example, mica, brittle mica, muscovite, soda mica, phlogopite, biotite, etc. can be used, and mica is preferred.
　本発明で用いる膨潤性層状粘土鉱物は、溶媒に添加することでチキソトロピーという性質を示す。チキソトロピーとは、剪断応力（振動）を受け続けると粘度が次第に低下し、液状になり、また、静止させると粘度が次第に上昇し、最終的に固体状になる現象をいう。本発明では、このチキソトロピーという性質を利用して、ゲル化電解質を初め液状化せしめ、電極全体にゲル化電解質を行き渡らせて、活物質の周囲を充分に覆うようにし、電解液のみを用いた時と同様に活物質－電解質の界面の接触抵抗を下げ、その後、固体化させることで、安全性の向上と電池性能を上げることを目的としている。すなわち、本発明は、集電体（例えば、Ａｌ箔、Ｃｕ箔等）上に電極活物質を含む電極材料を設けてなる電極に対して超音波等の物理的振動を与えながら、電極の表面に塗布したゲル化電解質を電極内部へ浸透せしめることにより、全ての活物質の表面を電解質で均一に覆い、活物質－電解質の界面の接触抵抗の減少を図ると同時に、放電生成物である多硫化リチウム（Ｌｉ２Ｓｘ：ｘ＝２～８）の電解質中への溶出を抑え、放電生成物を正極に保持したまま負極のＬｉ金属との反応を抑制することで、充放電サイクル特性の向上を図ったものである。 The swellable layered clay mineral used in the present invention exhibits thixotropic properties when added to a solvent. The thixotropy is a phenomenon in which the viscosity gradually decreases and becomes liquid when it continues to receive shear stress (vibration), and the viscosity gradually increases when it is stationary, and finally becomes solid. In the present invention, by utilizing this property of thixotropy, the gelled electrolyte is first liquefied, and the gelled electrolyte is spread over the entire electrode so as to sufficiently cover the periphery of the active material, and only the electrolyte is used. The purpose is to improve the safety and the battery performance by lowering the contact resistance at the active material-electrolyte interface as in the past, and then solidifying it. That is, the present invention provides an electrode surface while applying physical vibrations such as ultrasonic waves to an electrode in which an electrode material containing an electrode active material is provided on a current collector (for example, Al foil, Cu foil, etc.). By allowing the gelled electrolyte applied to the inside of the electrode to penetrate into the inside of the electrode, the surface of all active materials is uniformly covered with the electrolyte, and the contact resistance at the interface between the active material and the electrolyte is reduced, and at the same time, many discharge products are generated. By suppressing the elution of lithium sulfide (Li 2 S x : x = 2 to 8) into the electrolyte and suppressing the reaction with Li metal of the negative electrode while holding the discharge product on the positive electrode, the charge / discharge cycle characteristics are improved. It is an improvement.
　上記したリチウムイオン伝導性電解液と膨潤性層状粘土鉱物との混合割合は、電解液がチキソトロピー性を発現しうる量で適宜配合すれば良い。膨潤性層状粘土鉱物が多くなるにつれて固体化していき、チキソトロピー性が発現しなくなり、また、膨潤性層状粘土鉱物が少なくなるにつれて液体に近づくため、電解液を使用する場合と同じ問題が生じる。例えば、チキソトロピー性の点からは、膨潤性層状粘土鉱物の添加量は、この混合物の全重量基準で、２ｗｔ％～１０ｗｔ％程度の範囲であることが好ましい。２ｗｔ％未満であるとチキソトロピー性が発現しない傾向があり、１０ｗｔ％を超えると１０ｗｔ％と比べてゲル化が進行する傾向があり、チキソトロピー性は発現しない。 The mixing ratio of the lithium ion conductive electrolyte and the swellable layered clay mineral may be appropriately blended in such an amount that the electrolyte can exhibit thixotropy. As the amount of the swellable layered clay mineral increases, it becomes solid, so that thixotropy is not expressed, and as the amount of the swellable layered clay mineral decreases, the liquid becomes closer to the liquid. For example, from the viewpoint of thixotropy, the amount of the swellable layered clay mineral added is preferably in the range of about 2 wt% to 10 wt% based on the total weight of the mixture. If it is less than 2 wt%, the thixotropic property tends not to be expressed, and if it exceeds 10 wt%, gelation tends to proceed as compared with 10 wt%, and the thixotropic property is not expressed.
　本発明に係る活物質－電解質複合体の作製方法の実施の形態によれば、この作製方法は、上記活物質、上記導電助材、及び上記結着材を所定の割合（例えば、重量比４５：４５：１０）で混合した電極材料を上記集電体上に塗布してなる電極上に、上記ゲル化電解質を塗布し、次いでゲル化電解質の塗布された電極に対して、このゲル化電解質が液状化する強さの上記した振動（好ましくは、超音波振動）を与え、液状化したゲル化電解質を電極内へ均一に浸透せしめ、活物質の周りを電解質で覆うようにして作製するものである。 According to the embodiment of the method for producing an active material-electrolyte complex according to the present invention, this production method comprises a predetermined ratio (for example, a weight ratio of 45) of the active material, the conductive additive, and the binder. : 45: 10) The gelled electrolyte is applied to the electrode obtained by coating the electrode material mixed on the current collector, and then the gelled electrolyte is applied to the electrode coated with the gelled electrolyte. The above-mentioned vibration (preferably ultrasonic vibration) of the strength of liquefaction is applied, the liquefied gelled electrolyte is uniformly infiltrated into the electrode, and the active material is covered with the electrolyte. It is.
　上記活物質、上記導電助材、及び上記結着材は、例えば、次のようにして配合する。導電助材は、正極全体重量基準で１～５０ｗｔ％、好ましくは３０～５０ｗｔ％混合する。１ｗｔ％未満であると十分な導電性が発揮できず、５０ｗｔ％を超えると正極活物質の量が減ってしまい、容量が小さくなるという問題が生じる。結着材は、正極全体重量基準で１～５０ｗｔ％、好ましくは５～３０ｗｔ％混合する。１ｗｔ％未満であると結着能力が低くなってしまい、５０ｗｔ％を超えると正極活物質の量が減ってしまい、容量が小さくなるという問題が生じる。 The active material, the conductive auxiliary material, and the binder are blended as follows, for example. The conductive additive is mixed in an amount of 1 to 50 wt%, preferably 30 to 50 wt%, based on the total weight of the positive electrode. If it is less than 1 wt%, sufficient conductivity cannot be exhibited, and if it exceeds 50 wt%, the amount of the positive electrode active material is reduced, resulting in a problem that the capacity is reduced. The binder is mixed in an amount of 1 to 50 wt%, preferably 5 to 30 wt% based on the total weight of the positive electrode. If it is less than 1 wt%, the binding ability is lowered, and if it exceeds 50 wt%, the amount of the positive electrode active material is reduced, resulting in a problem that the capacity is reduced.
　本発明に係るリチウム－硫黄二次電池の実施の形態によれば、この二次電池は、上記ゲル化電解質を用いたものであって、このゲル化電解質を集電体上の正極材料内に浸透せしめ、正極複合体として用い、及び／又はこのゲル化電解質を集電体上の負極材料内に浸透せしめ、負極複合体として用いるものである。本発明のゲル化電解質を用いると、振動により液状化した電解質は、集電体となるＡｌ箔（正極）やＣｕ箔（負極）に塗布された正極（負極）材料内に自動的に浸透していき、電解質が活物質の全ての周囲を覆うことにより、活物質－電解質の界面の接触抵抗が低下し、また、放電生成物である多硫化リチウム（Ｌｉ２Ｓｘ：ｘ＝２～８）の電解質中への溶出を抑え、放電生成物を正極に保持したまま負極のＬｉ金属との反応を抑制することで、充放電サイクル特性が向上する。 According to the embodiment of the lithium-sulfur secondary battery according to the present invention, the secondary battery uses the gelled electrolyte, and the gelled electrolyte is placed in the positive electrode material on the current collector. It is impregnated and used as a positive electrode composite and / or this gelled electrolyte is infiltrated into a negative electrode material on a current collector and used as a negative electrode composite. When the gelled electrolyte of the present invention is used, the electrolyte liquefied by vibration automatically penetrates into the positive electrode (negative electrode) material applied to the Al foil (positive electrode) or Cu foil (negative electrode) as the current collector. As the electrolyte covers the entire periphery of the active material, the contact resistance at the active material-electrolyte interface decreases, and lithium polysulfide (Li 2 S x : x = 2-8) which is a discharge product ) Is suppressed, and the reaction with the Li metal of the negative electrode is suppressed while the discharge product is held on the positive electrode, thereby improving the charge / discharge cycle characteristics.
　本発明のリチウム－硫黄二次電池においては、正極と負極との短絡を防ぐために通常用いられるセパレータを用いても用いなくても良い。用いる場合には、通常の既知のセパレータであれば良い。例えば、多孔質ポリプロピレンフィルム（セルガード社製；商品名：セルガード＃２４００）等を用いることができる。 In the lithium-sulfur secondary battery of the present invention, a separator that is usually used to prevent a short circuit between the positive electrode and the negative electrode may or may not be used. In the case of using it, any ordinary known separator may be used. For example, a porous polypropylene film (manufactured by Celgard; trade name: Celgard # 2400) can be used.
　本発明によれば、図１（ａ）に示すように、活物質１１、結着材１２、導電助材１３を所定の割合で混合した電極材料を集電体１４上に塗布し、電極を得、この電極上に、有機溶媒含有の、リチウムイオン伝導性電解液と膨潤性層状粘土鉱物からなるゲル化電解質１５を塗布し、振動（例えば、超音波振動等）を与えることで、活物質－電解質複合体（電極複合体）を作製することができる。かくして作製した活物質－電解液複合体を電極として用い、既知の方法でリチウム－硫黄二次電池を組み立てることができる。ゲル化電解質に対して振動を与えることにより、図１（ａ）に示すように、ゲル化電解質１５は液状化し、活物質１１の全ての周囲を覆うようになる。 According to the present invention, as shown in FIG. 1 (a), an electrode material in which an active material 11, a binder 12, and a conductive additive 13 are mixed at a predetermined ratio is applied on a current collector 14, and the electrode is formed. An active material is obtained by applying an organic solvent-containing gelled electrolyte 15 containing a lithium ion conductive electrolyte and a swellable layered clay mineral to the electrode, and applying vibration (for example, ultrasonic vibration). -An electrolyte composite (electrode composite) can be produced. A lithium-sulfur secondary battery can be assembled by a known method using the active material-electrolyte composite thus prepared as an electrode. By applying vibration to the gelled electrolyte, as shown in FIG. 1A, the gelled electrolyte 15 is liquefied and covers the entire periphery of the active material 11.
　一方、図１（ｂ）に示すように、ゲル化電解質１５に振動を与えないと、電極上に塗布されたゲル化電解質１５は電極表面だけにとどまって、内部へと浸透せず、表面層の活物質１１の周囲を覆うだけである。そのため、所期の目的を達成することができない。図１（ｂ）における参照数字１１、１２、１３、及び１４は、図１（ａ）の場合と同じである。 On the other hand, as shown in FIG. 1 (b), if the gelled electrolyte 15 is not vibrated, the gelled electrolyte 15 applied on the electrode stays only on the electrode surface and does not penetrate into the inside. It only covers the periphery of the active material 11. Therefore, the intended purpose cannot be achieved. Reference numerals 11, 12, 13, and 14 in FIG. 1 (b) are the same as those in FIG. 1 (a).
　以下、実施例及び比較例を挙げて、本発明を具体的に説明する。 Hereinafter, the present invention will be specifically described with reference to examples and comparative examples.
　エーテル系有機溶媒である１、２－ジメトキシエタン（ＤＭＥ）２ｇ中に、膨潤性層状粘土鉱物である親油性の合成スメクタイト（コープケミカル（株）製、商品名：ルーセンタイトＳＴＮ）を１００ｍｇ添加し、充分に膨潤させた。電解液には３ｍｏｌ／ＬのＬｉＮ（ＣＦ３ＳＯ２）２（ＤＭＥ：ＤＯＬ＝９：１ｖｏｌ％）を用いた。上記充分に膨潤させたスメクタイト含有ジメトキシエタン溶液に対して、電解液を５６７ｍｇ添加し、ゲル化電解質を作製した。 100 mg of lipophilic synthetic smectite (trade name: Lucentite STN, manufactured by Co-op Chemical Co., Ltd.), a swellable layered clay mineral, was added to 2 g of 1,2-dimethoxyethane (DME), an ether organic solvent. Fully swollen. 3 mol / L LiN (CF 3 SO 2 ) 2 (DME: DOL = 9: 1 vol%) was used as the electrolytic solution. To the sufficiently swollen smectite-containing dimethoxyethane solution, 567 mg of an electrolytic solution was added to prepare a gelled electrolyte.
　実施例１で作製したゲル化電解質に超音波振動を与えた。振動を与えている間は、ゲル化電解質が液状化し、振動を停止し、その後放置することで、ゲル化（固体化）することを確認した。 The ultrasonic vibration was given to the gelled electrolyte produced in Example 1. While applying vibration, it was confirmed that the gelled electrolyte was liquefied, stopped vibrating, and then allowed to stand to gel (solidify).
　正極活物質として硫黄（Ｓ）（キシダ化学（株）製）、導電助材としてアセチレンブラック（ＡＢ）、結着材としてＰＶｄＦを用い、これらを重量比４５：４５：１０で混合した正極材料を集電体となるＡｌ箔上に塗布し、正極を得た。実施例１で作製したゲル化電解質を正極表面上に塗布し、超音波振動を与えることにより、ゲル化電解質を液状化せしめて、図１（ａ）に示すように正極内に浸透せしめ、活物質－電解質複合体を作製した。その結果、図１（ａ）に示すように、全ての活物質の表面が電解質で覆われていた。かくして作製した正極複合体を正極として用い、負極としてＬｉ金属を用いて２０３２型リチウム－硫黄二次電池を組み立て、充放電試験を行った。この場合、充放電の電流値は１９２．７４μＡ／ｃｍ２（０．１Ｃレートに相当）とし、カットオフ電圧を１．５－２．８Ｖとし、充放電を４３サイクル繰り返して行った。なお、単体硫黄を正極として用いているので、放電反応から測定を開始した。 A positive electrode material in which sulfur (S) (manufactured by Kishida Chemical Co., Ltd.) is used as a positive electrode active material, acetylene black (AB) is used as a conductive additive, PVdF is used as a binder, and these are mixed at a weight ratio of 45:45:10. It apply | coated on Al foil used as a collector, and the positive electrode was obtained. The gelled electrolyte produced in Example 1 was applied on the surface of the positive electrode, and ultrasonic vibration was applied to liquefy the gelled electrolyte, so that it penetrated into the positive electrode as shown in FIG. A substance-electrolyte complex was prepared. As a result, as shown in FIG. 1A, the surfaces of all the active materials were covered with the electrolyte. A 2032 type lithium-sulfur secondary battery was assembled using the positive electrode composite thus produced as a positive electrode and Li metal as a negative electrode, and a charge / discharge test was performed. In this case, the charge / discharge current value was 192.74 μA / cm 2 (corresponding to a 0.1 C rate), the cut-off voltage was 1.5-2.8 V, and charge / discharge was repeated 43 cycles. Since elemental sulfur was used as the positive electrode, measurement was started from the discharge reaction.
（比較例１）
　超音波振動を与えないこと以外は、実施例３記載の方法に従ってリチウム－硫黄二次電池を組み立て、充放電試験を行った。この場合、充放電の電流値は１９０μＡ／ｃｍ２（０．１Ｃレートに相当）とした。 (Comparative Example 1)
A lithium-sulfur secondary battery was assembled according to the method described in Example 3 except that no ultrasonic vibration was applied, and a charge / discharge test was performed. In this case, the charge / discharge current value was 190 μA / cm 2 (corresponding to a 0.1 C rate).
　実施例３及び比較例１で作製したリチウム－硫黄二次電池のそれぞれの１サイクル目の放電曲線を検討したところ、比較例１の場合の放電容量は、実施例３の場合の放電容量と比べて低かった。従って、本発明のゲル化電解質を用い、振動を与えて作製したリチウム－硫黄二次電池は、正極内に電解質が十分に浸透しており、振動を与えずに作製したリチウム－硫黄二次電池に比べて高いエネルギー密度が得られた。 When the discharge curves of the first cycle of the lithium-sulfur secondary batteries prepared in Example 3 and Comparative Example 1 were examined, the discharge capacity in Comparative Example 1 was compared with the discharge capacity in Example 3. It was low. Therefore, the lithium-sulfur secondary battery produced by applying vibration using the gelled electrolyte of the present invention is sufficiently penetrated into the positive electrode, and the lithium-sulfur secondary battery produced without applying vibration. A higher energy density was obtained.
（比較例２）
　電解液には３ｍｏｌ／ＬのＬｉＮ（ＣＦ３ＳＯ２）２（ＤＭＥ：ＤＯＬ＝９：１ｖｏｌ％）を用いた。セパレータとして多孔質ポリプロピレンフィルム（セルガード社製；商品名：セルガード＃２４００）を用いたこと以外は、実施例３記載の方法に従ってリチウム－硫黄二次電池を組みたて、充放電試験を行った。この場合、充放電の電流値は１８９．７５μＡ／ｃｍ２（０．１Ｃレートに相当）とし、充放電を４５サイクル繰り返して行った。なお、単体硫黄を正極として用いているので、放電反応から測定を開始した。 (Comparative Example 2)
3 mol / L LiN (CF 3 SO 2 ) 2 (DME: DOL = 9: 1 vol%) was used as the electrolytic solution. A lithium-sulfur secondary battery was assembled according to the method described in Example 3 except that a porous polypropylene film (manufactured by Celgard; trade name: Celgard # 2400) was used as the separator, and a charge / discharge test was performed. In this case, the charge / discharge current value was 189.75 μA / cm 2 (corresponding to a 0.1 C rate), and charge / discharge was repeated 45 cycles. Since elemental sulfur was used as the positive electrode, measurement was started from the discharge reaction.
　実施例３及び比較例２で作製したリチウム－硫黄二次電池のそれぞれの１サイクル目の充放電曲線を図２に示す。図２において、縦軸はＥ／Ｖ（Ｌｉ／Ｌｉ＋）であり、横軸は放電容量（ｍＡｈ／ｇ（活物質））である。図２から明らかなように、どちらも初期放電容量は１０００ｍＡｈ／ｇであり、高い放電容量を得ていることが分かる。 The charge / discharge curves of the first cycle of the lithium-sulfur secondary batteries produced in Example 3 and Comparative Example 2 are shown in FIG. In FIG. 2, the vertical axis represents E / V (Li / Li + ), and the horizontal axis represents discharge capacity (mAh / g (active material)). As is apparent from FIG. 2, the initial discharge capacity is 1000 mAh / g, indicating that a high discharge capacity is obtained.
　また、実施例３及び比較例２で作製したリチウム－硫黄二次電池のそれぞれの繰り返しサイクル特性で得られた放電容量を図３に示す。図３において、縦軸は放電容量（ｍＡｈ／ｇ（活物質））であり、横軸はサイクル回数である。図３から明らかなように、２０サイクル以降で実施例３の放電容量が比較例２の放電容量より大きくなり、サイクル特性が向上していることが分かる。 In addition, FIG. 3 shows the discharge capacities obtained with the respective repetitive cycle characteristics of the lithium-sulfur secondary batteries produced in Example 3 and Comparative Example 2. In FIG. 3, the vertical axis represents the discharge capacity (mAh / g (active material)), and the horizontal axis represents the number of cycles. As can be seen from FIG. 3, the discharge capacity of Example 3 is greater than the discharge capacity of Comparative Example 2 after 20 cycles, and the cycle characteristics are improved.
（比較例３）
　正極活物質として硫黄（Ｓ）（キシダ化学（株）製）、導電助材としてアセチレンブラック（ＡＢ）、結着材としてＰＶｄＦを用い、これらを重量比４５：４５：１０で混合した正極材料を集電体となるＡｌ箔上に塗布し、正極を得た。かくして作製した正極を用い、１ｍｏｌ／ＬのＬｉＣＬＯ４（ＥＣ（エチレンカーボネート）：ＤＥＣ（ジエチルカーボネート）＝１：１ｖｏｌ％）の電解液、セパレータとして多孔質ポリプロピレンフィルム（セルガード＃２４００）、負極としてＬｉ金属を用いて２０３２型リチウム－硫黄二次電池を組み立て、充放電試験を行った。この場合、充放電の電流値は３５５．０８μＡ／ｃｍ２（０．１Ｃレートに相当）とし、カットオフ電圧を１．４－３．０Ｖとし、充放電を３サイクル繰り返して行った。なお、単体硫黄を正極として用いているので、放電反応から測定を開始した。 (Comparative Example 3)
A positive electrode material in which sulfur (S) (manufactured by Kishida Chemical Co., Ltd.) is used as a positive electrode active material, acetylene black (AB) is used as a conductive additive, PVdF is used as a binder, and these are mixed at a weight ratio of 45:45:10. It apply | coated on Al foil used as a collector, and the positive electrode was obtained. Using the positive electrode thus prepared, 1 mol / L LiCLO 4 (EC (ethylene carbonate): DEC (diethyl carbonate) = 1: 1 vol%) electrolyte, porous polypropylene film (Celgard # 2400) as the separator, Li as the negative electrode A 2032 type lithium-sulfur secondary battery was assembled using metal, and a charge / discharge test was conducted. In this case, the charge / discharge current value was 355.08 μA / cm 2 (corresponding to a 0.1 C rate), the cut-off voltage was 1.4-3.0 V, and charge / discharge was repeated three cycles. Since elemental sulfur was used as the positive electrode, measurement was started from the discharge reaction.
　比較例３で作製したリチウム－硫黄二次電池の充放電曲線を１サイクル目（１ｓｔ）、２サイクル目（２ｎｄ）及び３サイクル目（３ｒｄ）について、図４に示す。図４において、縦軸はＥ／Ｖ（Ｌｉ／Ｌｉ＋）であり、横軸は放電容量（ｍＡｈ／ｇ（活物質））である。図４から明らかなように、カーボネート系有機溶媒を用いると放電は可能であるが、充電できていないことが分かる。 FIG. 4 shows charge / discharge curves of the lithium-sulfur secondary battery manufactured in Comparative Example 3 for the first cycle (1st), the second cycle (2nd), and the third cycle (3rd). In FIG. 4, the vertical axis represents E / V (Li / Li + ), and the horizontal axis represents discharge capacity (mAh / g (active material)). As can be seen from FIG. 4, when a carbonate-based organic solvent is used, discharging is possible but charging is not possible.
（比較例４）
　電解質としての１ｍｏｌ／ＬのＬｉＰＦ６（ＥＣ：ＤＥＣ＝１：１ｖｏｌ％）の電解液を用いた以外は、比較例３と同様の方法でリチウム－硫黄二次電池の作製と充放電測定を行った。その結果、比較例３と同様の結果が得られた。 (Comparative Example 4)
A lithium-sulfur secondary battery was prepared and charge / discharge measurement was performed in the same manner as in Comparative Example 3 except that an electrolyte solution of 1 mol / L LiPF 6 (EC: DEC = 1: 1 vol%) was used as the electrolyte. It was. As a result, the same results as in Comparative Example 3 were obtained.
　従って、以上の実施例及び比較例から、エーテル系有機溶媒によるゲル化電解質を用い、振動を与えて作製したリチウム－硫黄二次電池は、正極内に電解質が十分に浸透しており、放電生成物である多硫化リチウム（Ｌｉ２Ｓｘ：ｘ＝２～８）の電解質中への溶出が抑えられているので、放電生成物を正極に保持したまま負極のＬｉ金属との反応を抑制することができ、高い充放電特性が得られたことが分かる。 Therefore, from the above examples and comparative examples, the lithium-sulfur secondary battery produced by applying a gelled electrolyte with an ether-based organic solvent and giving vibrations sufficiently penetrates the positive electrode, and generates a discharge. Since the elution of lithium polysulfide (Li 2 S x : x = 2 to 8), which is a product, into the electrolyte is suppressed, the reaction with the Li metal in the negative electrode is suppressed while the discharge product is held in the positive electrode It can be seen that high charge / discharge characteristics were obtained.
　実施例１で用いた１，２－ジメトキシエタンの代わりに、エーテル系有機溶媒として、１，３－ジオキソラン、テトラヒドロフラン、２－メチルテトラヒドロフラン、１，４－ジオキサン、ジエチルエーテル、１，２－ジエトキシエタン、及びトリエチレングリコールジメチルエーテルをそれぞれ用いてゲル化電解質を作製し、実施例３記載の方法に従ってリチウム－硫黄二次電池を作製したところ、図２及び３に示した結果と同様な充放電曲線及び放電容量が得られることが分かった。 Instead of 1,2-dimethoxyethane used in Example 1, 1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethyl ether, 1,2-diethoxy were used as ether organic solvents. A gelled electrolyte was prepared using ethane and triethylene glycol dimethyl ether, respectively, and a lithium-sulfur secondary battery was prepared according to the method described in Example 3. As a result, a charge / discharge curve similar to the results shown in FIGS. And discharge capacity was found to be obtained.
　実施例３で用いた正極活物質である硫黄の代わりに、Ｌｉ２Ｓを用いたこと以外は、実施例３記載の方法に従ってリチウム－硫黄二次電池を作製したところ、図２及び３に示した結果と同様な充放電曲線及び放電容量が得られることが分かった。 A lithium-sulfur secondary battery was produced according to the method described in Example 3 except that Li 2 S was used instead of sulfur, which is the positive electrode active material used in Example 3, and the results shown in FIGS. It was found that the same charge / discharge curve and discharge capacity as those obtained were obtained.
　本実施例では実施例１で用いた合成スメクタイトの添加量を変え、実施例１記載の方法に従って、以下（１）～（７）の配合割合で電解質を作製し、得られた電解質に対して、実施例２に従って超音波振動を与えて、その状態を観察した。以下の合成スメクタイト添加量は、得られた電解質重量に対する割合である。
（１）合成スメクタイト：５０ｍｇ＋ＤＥＣ：２ｇ＋電解液：５６７ｍｇ（合成スメクタイト添加量：１．９１ｗｔ％）
（２）合成スメクタイト：１００ｍｇ＋ＤＥＣ：２ｇ＋電解液：５６７ｍｇ（合成スメクタイト添加量：３．７５ｗｔ％）
（３）合成スメクタイト：１５０ｍｇ＋ＤＥＣ：２ｇ＋電解液：５６７ｍｇ（合成スメクタイト添加量：５．５２ｗｔ％）
（４）合成スメクタイト２００ｍｇ＋ＤＥＣ：２ｇ＋電解液：５６７ｍｇ（合成スメクタイト添加量：７．２３ｗｔ％）
（５）合成スメクタイト３００ｍｇ＋ＤＥＣ：２ｇ＋電解液：５６７ｍｇ（合成スメクタイト添加量：１０．５ｗｔ％）
（６）合成スメクタイト４５０ｍｇ＋ＤＥＣ：２ｇ＋電解液：５６７ｍｇ（合成スメクタイト添加量：１４．９ｗｔ％）
（７）合成スメクタイト６５０ｍｇ＋ＤＥＣ：２ｇ＋電解液：５６７ｍｇ（合成スメクタイト添加量：２０．２ｗｔ％） In this example, the amount of the synthetic smectite used in Example 1 was changed, and an electrolyte was prepared according to the method described in Example 1 in the following proportions (1) to (7). According to Example 2, ultrasonic vibration was applied and the state was observed. The following synthetic smectite addition amount is a ratio with respect to the obtained electrolyte weight.
(1) Synthetic smectite: 50 mg + DEC: 2 g + electrolytic solution: 567 mg (addition amount of synthetic smectite: 1.91 wt%)
(2) Synthetic smectite: 100 mg + DEC: 2 g + electrolytic solution: 567 mg (additional amount of synthetic smectite: 3.75 wt%)
(3) Synthetic smectite: 150 mg + DEC: 2 g + Electrolytic solution: 567 mg (Additional amount of synthetic smectite: 5.52 wt%)
(4) Synthetic smectite 200 mg + DEC: 2 g + electrolytic solution: 567 mg (synthetic smectite addition amount: 7.23 wt%)
(5) Synthetic smectite 300 mg + DEC: 2 g + electrolytic solution: 567 mg (synthetic smectite addition amount: 10.5 wt%)
(6) Synthetic smectite 450 mg + DEC: 2 g + electrolytic solution: 567 mg (synthetic smectite addition amount: 14.9 wt%)
(7) Synthetic smectite 650 mg + DEC: 2 g + electrolytic solution: 567 mg (synthetic smectite addition amount: 20.2 wt%)
　上記作製物（１）～（７）のうち、（１）は、液体状態であり、チキソトロピー性は見られず、（２）は、チキソトロピー性を有し、（３）はチキソトロピー性を有し、（４）は、上記（３）よりもゲル化は進行したが、チキソトロピー性を有し、（５）は、上記（４）よりもゲル化が進行し、ほぼ固体に近く、チキソトロピー性は見られず、（６）は、ほぼ固体であり、チキソトロピー性は見られず、（７）は、ほぼ固体であり、チキソトロピー性は見られなかった。 Of the products (1) to (7), (1) is in a liquid state and no thixotropic property is observed, (2) has thixotropic properties, and (3) has thixotropic properties. (4) is more gelled than (3) but has thixotropic properties, (5) is more gelled than (4) and is almost solid, and thixotropic properties are No (6) was almost solid and no thixotropic property was seen, and (7) was almost solid and no thixotropic property was seen.
　上記（１）～（７）の結果から考えて、チキソトロピー性の点からは、膨潤性層状粘土鉱物の添加量は、２ｗｔ％～１０ｗｔ％程度の範囲であることが好ましい。 Considering the results of (1) to (7) above, from the viewpoint of thixotropy, the amount of the swellable layered clay mineral is preferably in the range of about 2 wt% to 10 wt%.
　実施例１で用いた合成スメクタイトの代わりに、ヘクトライト、ベントナイト、モンモリロナイトを用いたこと以外は、実施例３記載の方法に従ってリチウム－硫黄二次電池を作製したところ、図２及び３に示した結果と同様な充放電曲線及び放電容量が得られることが分かった。 A lithium-sulfur secondary battery was produced according to the method described in Example 3 except that hectorite, bentonite and montmorillonite were used instead of the synthetic smectite used in Example 1, and the results are shown in FIGS. It was found that the same charge / discharge curve and discharge capacity as the results were obtained.
　本発明によれば、複雑な作製プロセスを必要とせずに、高い充放電サイクル特性を維持したまま安全性を高めたリチウム－硫黄二次電池を提供できるので、リチウム－硫黄二次電池を使用する各種産業において利用可能である。 According to the present invention, it is possible to provide a lithium-sulfur secondary battery with improved safety while maintaining a high charge / discharge cycle characteristic without requiring a complicated manufacturing process. Therefore, the lithium-sulfur secondary battery is used. It can be used in various industries.
１１　活物質　　　　　　　　　　　　　　１２　結着材
１３　導電助材　　　　　　　　　　　　　１４　集電体
１５　ゲル化電解質　  11 Active Material 12 Binder 13 Conductive Aid 14 Current Collector 15 Gelled Electrolyte

Claims (10)

  1. 活物質、導電助材、及び結着材を所定の割合で混合した電極材料であって、正極活物質が単体硫黄又はリチウム含有硫化物である電極材料を集電体上に設けた電極上に、エーテル系有機溶媒を含む、リチウムイオン伝導性電解液と膨潤性層状粘土鉱物との混合物からなるゲル化電解質を設け、この電極に対して、このゲル化電解質が液状化する強さの振動を与えてなることを特徴とする活物質－電解質複合体。 An electrode material in which an active material, a conductive additive, and a binder are mixed at a predetermined ratio, and an electrode material in which the positive electrode active material is elemental sulfur or lithium-containing sulfide is provided on the current collector A gelled electrolyte comprising a mixture of a lithium ion conductive electrolyte containing an ether organic solvent and a swellable layered clay mineral is provided, and the vibration of the strength that the gelled electrolyte liquefies is applied to the electrode. An active material-electrolyte complex characterized by being given.
  2. 請求項１記載の活物質－電解質複合体において、膨潤性層状粘土鉱物は、スメクタイト系層状粘土鉱物、又は雲母系層状粘土鉱物であることを特徴とする活物質－電解質複合体。 2. The active material-electrolyte complex according to claim 1, wherein the swellable layered clay mineral is a smectite-based layered clay mineral or a mica-based layered clay mineral.
  3. 請求項１又は２記載の活物質－電解質複合体において、リチウム含有硫化物が、硫化リチウム（Ｌｉ２Ｓ）であることを特徴とする活物質－電解質複合体。 3. The active material-electrolyte complex according to claim 1, wherein the lithium-containing sulfide is lithium sulfide (Li 2 S).
  4. 活物質、導電助材、及び結着材を所定の割合で混合した電極材料であって、正極活物質が単体硫黄又はリチウム含有硫化物である電極材料を集電体上に設けてなる電極上に、エーテル系有機溶媒を含む、リチウムイオン伝導性電解液と膨潤性層状粘土鉱物との混合物からなるゲル化電解質を塗布し、次いでゲル化電解質の塗布された電極に対して、このゲル化電解質が液状化する強さの振動を与え、ゲル化電解質を液状化して電極内へ浸透せしめ活物質－電解質複合体を作製することを特徴とする活物質－電解質複合体の作製方法。 An electrode material in which an active material, a conductive additive, and a binder are mixed at a predetermined ratio, and an electrode material in which the positive electrode active material is elemental sulfur or lithium-containing sulfide is provided on a current collector A gelled electrolyte comprising a mixture of a lithium ion conductive electrolyte and a swellable layered clay mineral containing an ether-based organic solvent, and then the gelled electrolyte is applied to the electrode coated with the gelled electrolyte. A method for producing an active material-electrolyte complex, characterized in that an active material-electrolyte complex is produced by applying a vibration of strength that liquefies and liquefying the gelled electrolyte to penetrate into the electrode.
  5. 請求項４記載の活物質－電解質複合体の作製方法において、膨潤性層状粘土鉱物は、スメクタイト系層状粘土鉱物、又は雲母系層状粘土鉱物であることを特徴とする活物質－電解質複合体の作製方法。 5. The method for producing an active material-electrolyte complex according to claim 4, wherein the swellable layered clay mineral is a smectite-based layered clay mineral or a mica-based layered clay mineral. Method.
  6. 請求項４又は５記載の活物質－電解質複合体の作製方法において、リチウム含有硫化物が、硫化リチウム（Ｌｉ２Ｓ）であることを特徴とする活物質－電解質複合体の作製方法。 6. The method for producing an active material-electrolyte composite according to claim 4, wherein the lithium-containing sulfide is lithium sulfide (Li 2 S).
  7. 請求項１～３のいずれか１項記載の活物質－電解質複合体を用いたことを特徴とする全固体型リチウム－硫黄二次電池。 An all-solid-state lithium-sulfur secondary battery comprising the active material-electrolyte complex according to any one of claims 1 to 3.
  8. 請求項７記載の活物質－電解質複合体が正極活物質－電解質複合体であることを特徴とする全固体型リチウム－硫黄二次電池。 8. An all-solid-state lithium-sulfur secondary battery, wherein the active material-electrolyte complex according to claim 7 is a positive electrode active material-electrolyte complex.
  9. 請求項７記載の活物質－電解質複合体が負極活物質－電解質複合体であることを特徴とする全固体型リチウム－硫黄二次電池。 8. An all-solid-state lithium-sulfur secondary battery, wherein the active material-electrolyte complex according to claim 7 is a negative electrode active material-electrolyte complex.
  10. 請求項７記載の活物質－電解質複合体が、正極活物質－電解質複合体及び負極活物質－電解質複合体であることを特徴とする全固体型リチウム－硫黄二次電池。 8. An all-solid-state lithium-sulfur secondary battery, wherein the active material-electrolyte complex according to claim 7 is a positive electrode active material-electrolyte complex and a negative electrode active material-electrolyte complex.
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CN108292782A (en) * 2016-04-22 2018-07-17 株式会社Lg化学 Lithium-sulfur cell electrolyte and lithium-sulfur cell comprising it
CN108292782B (en) * 2016-04-22 2021-05-11 株式会社Lg化学 Electrolyte for lithium-sulfur battery and lithium-sulfur battery comprising same
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