WO2020085811A1 - Batterie secondaire au lithium-soufre - Google Patents

Batterie secondaire au lithium-soufre Download PDF

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Publication number
WO2020085811A1
WO2020085811A1 PCT/KR2019/014039 KR2019014039W WO2020085811A1 WO 2020085811 A1 WO2020085811 A1 WO 2020085811A1 KR 2019014039 W KR2019014039 W KR 2019014039W WO 2020085811 A1 WO2020085811 A1 WO 2020085811A1
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lithium
solvent
secondary battery
sulfur secondary
positive electrode
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PCT/KR2019/014039
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English (en)
Korean (ko)
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박인태
양두경
최영철
김수현
이창훈
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주식회사 엘지화학
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Priority claimed from KR1020190131538A external-priority patent/KR20200047365A/ko
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to JP2020545656A priority Critical patent/JP7065990B2/ja
Priority to CN201980018365.8A priority patent/CN111837260A/zh
Priority to EP19874836.0A priority patent/EP3751640A4/fr
Priority to US16/971,177 priority patent/US20210104745A1/en
Publication of WO2020085811A1 publication Critical patent/WO2020085811A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—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
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a lithium-sulfur secondary battery.
  • lithium-ion secondary batteries with relatively low weight-to-weight energy storage density ( ⁇ 250 Wh / kg) are used in these products. There is a limit to the application.
  • lithium-sulfur secondary batteries are in the spotlight as the next generation secondary battery technology because they can theoretically realize a high weight-to-weight energy storage density ( ⁇ 2,600 Wh / kg).
  • the lithium-sulfur secondary battery refers to a battery system using a sulfur-based material having an S-S bond (Sulfur-Sulfur Bond) as a positive electrode active material and a lithium metal as a negative electrode active material.
  • Sulfur the main material of the positive electrode active material, has an advantage of having a large amount of resources worldwide, not toxic, and having a low weight per atom.
  • lithium In the lithium-sulfur secondary battery, lithium, a negative electrode active material, is released and ionized during discharge, and is oxidized, and a sulfur-based material, a positive electrode active material, is absorbed and reduced.
  • the oxidation reaction of lithium is a process in which lithium metal releases electrons and is converted into lithium cation form.
  • the reduction reaction of sulfur is a process in which the SS bond accepts two electrons and is converted into a sulfur anion form. The lithium cation generated by the oxidation reaction of lithium is transferred to the positive electrode through the electrolyte, and combines with the sulfur anion generated by the reduction reaction of sulfur to form a salt.
  • sulfur before discharge has a cyclic S 8 structure, which is converted to lithium polysulfide (LiS x ) by a reduction reaction.
  • lithium polysulfide LiS x
  • lithium sulfide Li 2 S
  • sulfur As a positive electrode active material, sulfur has a characteristic of low electrical conductivity, so it is difficult to secure reactivity with electrons and lithium ions in a solid phase form.
  • the existing lithium-sulfur secondary battery In order to improve the reactivity of the sulfur, the existing lithium-sulfur secondary battery generates an intermediate polysulfide in the form of Li 2 S x to induce a liquid phase reaction and improve reactivity.
  • an ether-based solvent such as dioxolane or dimethoxyethane, which is highly soluble in lithium polysulfide, is used as a solvent for the electrolyte.
  • the existing lithium-sulfur secondary battery constructs a catholyte type lithium-sulfur secondary battery system to improve reactivity, in which case, due to the characteristics of lithium polysulfide dissolved in the electrolyte, the reactivity of sulfur according to the content of the electrolyte And lifetime characteristics are affected.
  • a low content of electrolyte In order to build a high energy density, a low content of electrolyte must be injected, but as the content of the electrolyte decreases, the concentration of lithium polysulfide in the electrolyte increases, and it is difficult to operate a normal battery due to a decrease in fluidity and an increase in side reactions.
  • Non-Patent Document 1 Abbas Fotouhi et al., Lithium-Sulfur Battery Technology Readiness and Applications ⁇ A Review, Energys 2017, 10, 1937.
  • the present invention is to provide a lithium-sulfur secondary battery capable of realizing a lithium-sulfur secondary battery having a high energy density by adjusting a positive electrode and an electrolyte to specific conditions.
  • the present invention provides a lithium-sulfur secondary battery comprising an anode, a cathode, a separator, and an electrolyte.
  • the positive electrode has an SC factor value of 0.45 or more represented by Equation 1 below.
  • P is the porosity (%) of the positive electrode active material layer in the positive electrode
  • L is the mass of sulfur per unit area of the positive electrode active material layer in the positive electrode (mg / cm 2)
  • ⁇ is 10 (constant).
  • the electrolyte solution includes a solvent and a lithium salt
  • the solvent includes a first solvent having a DV 2 factor value of 1.75 or less represented by Equation 2 below, and a second solvent being a fluorinated ether-based solvent.
  • the first solvent has a DV 2 factor value of 1.5 or less.
  • the lithium-sulfur secondary battery has an NS factor value represented by Equation 3 below 3.5 or less.
  • the lithium-sulfur secondary battery has an ED factor value of 850 or more represented by Equation 4 below.
  • V is the nominal discharge voltage for Li / Li + (V)
  • D is the density of the electrolyte (g / cm 3)
  • C is the discharge capacity at discharge at 0.1C rate (mAh / g)
  • SC factor I is the same as the value defined by Equation 1 above.
  • the first solvent is selected from the group consisting of propionitrile, dimethylacetamide, dimethylformamide, gamma-butyrolactone, triethylamine, 1-iodopropane, and combinations thereof. .
  • the second solvent is 1H, 1H, 2'H, 3H-decafluorodipropyl ether, difluoromethyl 2,2,2-trifluoroethyl ether, 1,2, 2,2-tetrafluoroethyl trifluoromethyl ether, 1,1,2,3,3,3-hexafluoropropyl difluoromethyl ether, 1H, 1H, 2'H, 3H-decafluorodipropyl Ether, pentafluoroethyl 2,2,2-trifluoroethyl ether, 1H, 1H, 2'H-perfluorodipropyl ether and combinations thereof.
  • the solvent comprises 1 to 50% by weight of the first solvent.
  • the solvent comprises 50 to 99% by weight of the second solvent.
  • the solvent comprises a first solvent and a second solvent in a weight ratio of 3: 7 to 1: 9.
  • the lithium-sulfur secondary battery according to the present invention has a high energy density that was difficult to implement with a conventional lithium-sulfur secondary battery by controlling the positive electrode and the electrolyte to specific conditions.
  • the present invention provides a lithium-sulfur secondary battery comprising an anode, a cathode, a separator, and an electrolyte.
  • the lithium-sulfur secondary battery according to the present invention includes a positive electrode having a low porosity and a high loading amount of sulfur as a positive electrode active material. When the porosity is lowered at the positive electrode and the content of the positive electrode active material is increased, the energy density of the battery containing the positive electrode increases. However, if the porosity of the anode is minimized and the sulfur content is maximized in the lithium-sulfur secondary battery, the ratio of the electrolyte solution per unit sulfur content decreases.
  • the target is It is difficult to achieve one performance.
  • it is intended to provide a lithium-sulfur secondary battery having a higher energy density than an existing lithium-sulfur secondary battery in actual implementation by limiting conditions related to sulfur at the positive electrode and specifying appropriate electrolyte conditions.
  • the positive electrode is not particularly limited, but may be a lithium thin film or a positive electrode active material layer formed on one surface of the current collector. If, when the positive electrode is a positive electrode active material layer is formed on one surface of the current collector, the positive electrode may be prepared by applying a positive electrode active material slurry containing a positive electrode active material on one surface of the current collector and drying it. The slurry may further include additives such as a binder and a conductive material, a filler, and a dispersant in addition to the positive electrode active material.
  • the positive active material may include elemental sulfur (S 8 ), a sulfur-based compound, or a mixture thereof.
  • the binder is a component that assists the bonding of the positive electrode active material and the conductive material and bonding to the current collector, and may be usually added in an amount of 1% to 30% by weight based on the total amount of the positive electrode active material slurry.
  • the binder is not particularly limited, for example, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidenefluoride, polyacrylonitrile, polymethylmethacryl Late (polymethylmethacrylate), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene It may be one or a mixture of two or more selected from the group consisting of monomers (EPDM), sulfonated EPDM, styrene-butylene
  • the conductive material is not particularly limited, for example, graphite such as natural graphite or artificial graphite; Carbon blacks such as carbon black (super-p), acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and denka black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; And conductive materials such as polyphenylene derivatives.
  • the conductive material may be a content of 0.05% to 5% by weight based on the total weight of the positive electrode active material slurry.
  • the filler may be used as a component that suppresses the expansion of the positive electrode, if necessary, whether or not to use it, and does not cause any chemical change in the battery, but is not particularly limited if it is a fibrous material, for example, olefin polymers such as polyethylene polypropylene; It may be a fibrous material such as glass fiber, carbon fiber.
  • the dispersant is not particularly limited, but may be, for example, isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or the like.
  • the coating may be performed by a method commonly known in the art, but, for example, the positive electrode active material slurry is distributed on one side of the positive electrode current collector and then uniformly dispersed using a doctor blade or the like. You can. In addition, it may be performed through methods such as die casting, comma coating, and screen printing.
  • the drying is not particularly limited, but may be performed within 1 day in a vacuum oven at 50 ° C to 200 ° C.
  • the positive electrode of the present invention manufactured by the above-described material and method is divided by the SC factor value represented by the following equation (1).
  • the lithium-sulfur secondary battery according to the present invention realizes a high energy density by organic bonding of the cathode, separator, and electrolyte as well as the above-described positive electrode, and according to an embodiment of the present invention, the lithium-sulfur secondary battery has high energy
  • the SC factor value may be 0.45 or more, preferably 0.5 or more.
  • the upper limit of the SC factor value is not particularly limited, but considering the embodiment of the actual lithium-sulfur secondary battery, the SC factor value may be 4.5 or less.
  • the SC factor value is 0.45 or more, in the case of a conventional lithium-sulfur secondary battery, performance such as energy density of the battery decreases in actual implementation, but in the case of a lithium-sulfur secondary battery according to the present invention, even in actual implementation Its performance is maintained without deterioration.
  • the negative electrode includes a negative electrode current collector, and a negative electrode active material layer formed on the negative electrode current collector.
  • the negative active material layer includes a negative active material, a binder, and a conductive material.
  • a material capable of reversibly intercalating or deintercalating lithium ions (Li + ), a material capable of reversibly forming a lithium-containing compound by reacting with lithium ions, lithium metal or lithium alloy Can be used.
  • the material capable of reversibly occluding or releasing lithium ions (Li + ) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof.
  • a material capable of reversibly forming a lithium-containing compound by reacting with the lithium ion (Li + ) may be, for example, tin oxide, titanium nitrate or silicon.
  • the lithium alloy is, for example, lithium (Li) and sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium ( Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).
  • the binder is not limited to the above-described binder, and any material that can be used as a binder in the related art is possible.
  • Materials such as a current collector other than the negative electrode active material and the conductive material, and materials and methods used in the positive electrode described above may be used.
  • the separator is a physical separator having a function of physically separating an electrode, and can be used without particular limitation as long as it is used as a normal separator. desirable.
  • the separator enables the transport of lithium ions between the positive electrode and the negative electrode while separating or insulating the positive electrode and the negative electrode from each other.
  • the separator may be made of a material having a porosity of 30 to 50% and a non-conductive or insulating material.
  • a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer may be used. It is possible to use a non-woven fabric made of high melting point glass fiber or the like. Among them, a porous polymer film is preferably used.
  • an ethylene homopolymer (polyethylene) polymer film is used as a separator, and a polyimide nonwoven fabric is used as a buffer layer.
  • the polyethylene polymer film preferably has a thickness of 10 to 25 ⁇ m and a porosity of 40 to 50%.
  • the electrolyte solution is a non-aqueous electrolyte solution containing a lithium salt, and is composed of a lithium salt and a solvent.
  • the electrolyte has a density of less than 1.5 g / cm 3.
  • the electrolyte has a density of 1.5 g / cm 3 or more, it is difficult to realize a high energy density of the lithium-sulfur secondary battery due to an increase in the weight of the electrolyte.
  • the lithium salt is a material that can be easily dissolved in a non-aqueous organic solvent, for example, LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiB (Ph) 4 , LiC 4 BO 8 , LiPF 6 , LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, LiSO 3 CH 3, LiSO 3 CF 3, LiSCN, LiC (CF 3 SO 2) 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2 ) 2 , LiN (SO 2 F) 2 , chloro borane lithium, lower aliphatic lithium carboxylate, lithium tetraphenyl borate, and lithium imide.
  • the lithium salt may be preferably a lithium imide such as LiTFSI.
  • the concentration of the lithium salt is 0.1 to 8.0M, depending on several factors such as the exact composition of the electrolyte mixture, the solubility of the salt, the conductivity of the dissolved salt, the conditions for charging and discharging the battery, the working temperature and other factors known in the field of lithium secondary batteries. , Preferably 0.5 to 5.0M, more preferably 1.0 to 3.0M. If the concentration of the lithium salt is less than the above range, the conductivity of the electrolyte solution may be lowered to deteriorate the battery performance, and if it exceeds the above range, the mobility of the lithium ion (Li + ) may decrease due to an increase in the viscosity of the electrolyte solution. It is desirable to select an appropriate concentration.
  • the solvent includes a first solvent and a second solvent.
  • the first solvent has the highest dipole moment per unit volume among the components contained in the solvent by 1% by weight or more, and thus is characterized by having a high dipole moment and a low viscosity.
  • a solvent having a high dipole moment is used, it has an effect of improving the solid phase reactivity of sulfur, and this effect can be excellently expressed when the solvent itself has a low viscosity.
  • the first solvent is classified by the DV 2 factor represented by Equation 2 below.
  • the DV 2 factor value may be 1.75 or less, preferably 1.5 or less.
  • the lower limit of the DV 2 factor value is not particularly limited, but considering the embodiment of the actual lithium-sulfur secondary battery, the DV 2 factor value may be 0.1 or more.
  • the type is not particularly limited, but propionitrile (Propionitrile), dimethylacetamide (Dimethylacetamide), dimethylformamide (Dimethylformamide), gamma- Butyrolactone (Gamma-Butyrolactone), triethylamine (Triethylamine), can be selected from the group consisting of 1-iodopropane (1-iodopropane) and combinations thereof.
  • the first solvent may include 1 to 50% by weight, preferably 5 to 40% by weight, more preferably 10 to 30% by weight based on the solvent constituting the electrolyte solution.
  • the solvent according to the present invention includes the first solvent within the above-mentioned weight percent range, the performance of the battery may be improved even when used with a positive electrode having a low porosity and a high loading amount of sulfur as a positive electrode active material.
  • the lithium-sulfur secondary battery of the present invention may be further classified by an NS factor combining the SC factor and the DV 2 factor.
  • the NS factor is represented by Equation 3 below.
  • the SC factor is the same as the value defined by Equation 1
  • the DV 2 factor is the same as the value defined by Equation 2.
  • the NS factor value may be 3.5 or less, preferably 3.0 or less, and more preferably 2.7 or less.
  • the lower limit of the NS factor value is not particularly limited, but considering the embodiment of the actual lithium-sulfur secondary battery, the NS factor value may be 0.1 or more. When the NS factor value is adjusted within the above range, the performance improvement effect of the lithium-sulfur secondary battery may be more excellent.
  • the second solvent in the present invention is a fluorinated ether-based solvent.
  • a solvent such as dimethoxyethane or dimethylcarbonate was used as a diluent.
  • a second solvent is added together with the first solvent to drive the positive electrode according to the present invention.
  • the second solvent is a fluorinated ether-based solvent generally used in the art, the type is not particularly limited, but 1H, 1H, 2'H, 3H-decafluorodipropyl ether (1H, 1H, 2 ' H, 3H-Decafluorodipropyl ether), Difluoromethyl 2,2,2-trifluoroethyl ether, 1,2,2,2-tetrafluoroethyl trifluoro Methyl ether (1,2,2,2-Tetrafluoroethyl trifluoromethyl ether), 1,1,2,3,3,3-hexafluoropropyl difluoromethyl ether (1,1,2,3,3,3- Hexafluoropropyl difluoromethyl ether), 1H, 1H, 2'H, 3H-decafluorodipropyl ether (1H, 1H, 2'H, 3H-Decafluorodipropyl ether), pentafluoroethyl 2,2,
  • the second solvent may include 50 to 99% by weight, preferably 60 to 95% by weight, more preferably 70 to 90% by weight based on the solvent constituting the electrolyte solution.
  • the solvent according to the present invention includes the second solvent within the above-mentioned weight percent range, the performance of the battery is improved even when used with a positive electrode having a low porosity and a positive loading amount of sulfur as a positive electrode active material, as in the first solvent.
  • the second solvent may be included in the electrolyte in an amount equal to or higher than the first solvent.
  • the solvent comprises a first solvent and a second solvent in a weight ratio of 1: 1 to 1: 9, preferably 3: 7 to 1: 9 (first solvent: second solvent). You can.
  • the non-aqueous electrolyte solution for a lithium-sulfur battery of the present invention may further include a nitric acid or nitrous acid compound as an additive.
  • the nitric acid or nitrite-based compound has an effect of forming a stable film on the lithium electrode and improving charging and discharging efficiency.
  • the nitric acid or nitrite-based compound is not particularly limited in the present invention, but lithium nitrate (LiNO 3 ), potassium nitrate (KNO 3 ), cesium nitrate (CsNO 3 ), barium nitrate (Ba (NO 3 ) 2 ), ammonium nitrate Inorganic nitric acid or nitrite compounds such as (NH 4 NO 3 ), lithium nitrite (LiNO 2 ), potassium nitrite (KNO 2 ), cesium nitrite (CsNO 2 ), and ammonium nitrite (NH 4 NO 2 ); Organic nitric acid such as methyl nitrate, dialkyl imidazolium nitrate, guanidine nitrate, imidazolium nitrate, pyridinium nitrate, ethyl nitrite, propyl nitrite, butyl nitrite, pentyl nitrite, oct
  • the non-aqueous electrolyte may further include other additives for the purpose of improving charge / discharge characteristics, flame retardancy, and the like.
  • the additives include pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexatriphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazoli Dinon, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol, aluminum trichloride, fluoroethylene carbonate (FEC), propene sulfone (PRS), vinylene carbonate ( VC) and the like.
  • FEC fluoroethylene carbonate
  • PRS propene sulfone
  • VC vinylene carbonate
  • the lithium-sulfur secondary battery of the present invention may be manufactured by placing a separator between an anode and a cathode to form an electrode assembly, and the electrode assembly is placed in a cylindrical battery case or a square battery case and then injected with electrolyte. Alternatively, after laminating the electrode assembly, it may be prepared by impregnating it with an electrolyte and sealing the resulting product in a battery case.
  • the lithium-sulfur secondary battery according to the present invention is divided by an ED factor value represented by the following Equation 4.
  • V is the nominal discharge voltage for Li / Li + (V)
  • D is the density of the electrolyte (g / cm 3)
  • C is the discharge capacity at discharge at 0.1C rate (mAh / g)
  • SC factor is It is the same as the value defined by Equation 1 above.
  • the ED factor value may be 850 or more, preferably 870 or more, and more preferably 891 or more.
  • the upper limit of the ED factor value is not particularly limited, but considering an embodiment of an actual lithium-sulfur secondary battery, the ED factor value may be 10,000 or less.
  • the range of the ED factor value means that the lithium-sulfur secondary battery according to the present invention can realize an improved energy density than the existing lithium-sulfur secondary battery.
  • a composition for forming a positive electrode active material layer was prepared by mixing water as a solvent, and mixing sulfur, super-P, SP, a conductive material, and a binder with a ball mill. At this time, Denka Black was used as the conductive material, and a mixed binder of SBR and CMC was used as the binder, and the mixing ratio was sulfur and SP (9: 1 ratio) by weight ratio: conductive material: binder was 90:10:10 It was made possible.
  • the prepared positive electrode active material layer-forming composition was applied to an aluminum current collector and dried to prepare a positive electrode (energy density of the positive electrode: 6.18 mAh / cm 2).
  • the porosity of the positive electrode active material layer calculated by measuring electrode weight and electrode thickness (using TESA- ⁇ HITE equipment manufactured by TESA) in the prepared positive electrode was 74%, and the mass of sulfur per unit area of the positive electrode active material layer was 3.75 mg / cm 2.
  • the SC factor value calculated based on this was 0.50.
  • the electrolyte solution was prepared by dissolving 3M concentration of lithium bis (trifluoromethyl sulfonyl) imide (LiTFSI) in an organic solvent, wherein the organic solvent was propionitrile (first solvent) and 1H, 1H, 2 A solvent in which 'H, 3H-decafluorodipropyl ether (second solvent) was mixed in a 3: 7 weight ratio was used.
  • LiTFSI lithium bis (trifluoromethyl sulfonyl) imide
  • the dipole moment per unit volume in the first solvent was 97.1 D ⁇ mol / L, and the viscosity (25 ° C.) of the solvent measured using a BROOKFIELD AMETEK LVDV2T-CP viscometer was 0.38 cP. The DV 2 factor value calculated based on this was 0.39.
  • a lithium-sulfur secondary battery was manufactured in the same manner as in Example 1.
  • a lithium-sulfur secondary battery was manufactured in the same manner as in Example 1.
  • a lithium-sulfur secondary battery was manufactured in the same manner as in Example 1.
  • a lithium-sulfur secondary battery was manufactured in the same manner as in Example 1.
  • LiTFSI lithium bis (trifluoromethyl sulfonyl) imide
  • LiTFSI lithium bis (trifluoromethyl sulfonyl) imide
  • LiTFSI lithium bis (trifluoromethyl sulfonyl) imide
  • LiTFSI lithium bis (trifluoromethyl sulfonyl) imide
  • LiTFSI lithium bis (trifluoromethyl sulfonyl) imide
  • the dipole moment per unit volume was 59.29D ⁇ mol / L
  • the solvent viscosity (25 ° C) was 0.61cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 1.02 dimethylacetamide was used.
  • the dipole moment per unit volume instead of propionitrile as the first solvent was 71.04D ⁇ mol / L
  • the solvent viscosity (25 ° C) was 0.51cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 0.71 dimethylformamide was used.
  • the dipole moment per unit volume is 84.91D ⁇ mol / L
  • the solvent viscosity (25 ° C) is 1.03cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that gamma-butyrolactone of 1.21 was used.
  • the dipole moment per unit volume is 136.8 D ⁇ mol / L instead of propionitrile as the first solvent, the solvent viscosity (25 ° C.) is 0.42 cP, and the DV 2 factor value calculated based on this
  • a lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 0.31 triethylamine was used.
  • the dipole moment per unit volume is 32.42D ⁇ mol / L instead of propionitrile as the first solvent, the solvent viscosity (25 ° C) is 0.45cP, and the DV 2 factor value calculated based on this
  • a lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 1.40 i-iodopropane was used.
  • the dipole moment per unit volume is 33.66D ⁇ mol / L
  • the solvent viscosity (25 ° C) is 0.7cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 2.07, 1,3-dioxolane (1,3-Dioxolane) was used.
  • the dipole moment per unit volume was 20.54 D ⁇ mol / L
  • the solvent viscosity (25 ° C.) was 0.48 cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 2.33, 1,2-dimethoxyethane was used.
  • the dipole moment per unit volume is 25.79 D ⁇ mol / L
  • the solvent viscosity (25 ° C.) is 0.58 cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 2.24 tetrahydrofuran was used.
  • the dipole moment per unit volume was 59.43D ⁇ mol / L
  • the solvent viscosity (25 ° C) was 1.16cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 1.95 dimethyl sulfoxide was used.
  • the dipole moment per unit volume is 96.13D ⁇ mol / L
  • the solvent viscosity (25 ° C) is 1.71cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 1.77 propylene carbonate was used.
  • the dipole moment per unit volume was 5.74 D ⁇ mol / L
  • the solvent viscosity (25 ° C.) was 0.57 cP
  • the DV 2 factor value calculated based on this A lithium-sulfur secondary battery was manufactured in the same manner as in Example 1, except that 9.93 dimethyl carbonate was used.
  • Electrolyte composition SC factor ED factor Example 1 First electrolyte composition 1 ) 0.50 1004.6 Example 2 0.45 893.0 Comparative Example 1 0.30 593.1 Comparative Example 2 0.35 695.6 Comparative Example 3 0.41 819.4 Comparative Example 4 Second electrolyte composition 2 ) 0.50 877.9 Comparative Example 5 0.45 890.8 Comparative Example 6 0.30 654.4 Comparative Example 7 0.35 761.4 Comparative Example 8 0.41 882.5 1)
  • First electrolyte composition Propionitrile: 1H, 1H, 2'H, 3H-Decafluorodipropyl ether (3: 7, w / w) solvent, 3.0M LiTFSI 2)
  • Second electrolyte composition 1,3-Dioxolan: Dimethyl ether (1: 1, v / v) solvent, 1.0M LiTFSI, 1.0 wt% LiNO 3
  • the lithium-sulfur secondary batteries according to Examples 1 and 2 have an ED factor value of 891 or more that cannot be realized by a lithium-sulfur secondary battery having a second electrolyte composition or an SC factor of 0.41 or less. Can have This means that the lithium-sulfur secondary battery according to the present invention can realize a higher energy density that could not be realized in the existing lithium-sulfur secondary battery.

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Abstract

La présente invention concerne une batterie secondaire au lithium-soufre comprenant une cathode, une anode, un séparateur et une solution électrolytique. La cathode a un facteur SC, représenté par la formule mathématique 1, de 0,45 ou plus. La solution électrolytique renferme un solvant et un sel de lithium, et le solvant renferme un premier solvant ayant un facteur DV2 représenté par la formule mathématique 2, de 1,7 ou moins, et un second solvant qui est un solvant à base d'éther fluoré.
PCT/KR2019/014039 2018-10-26 2019-10-24 Batterie secondaire au lithium-soufre WO2020085811A1 (fr)

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JP2020545656A JP7065990B2 (ja) 2018-10-26 2019-10-24 リチウム‐硫黄二次電池
CN201980018365.8A CN111837260A (zh) 2018-10-26 2019-10-24 锂硫二次电池
EP19874836.0A EP3751640A4 (fr) 2018-10-26 2019-10-24 Batterie secondaire au lithium-soufre
US16/971,177 US20210104745A1 (en) 2018-10-26 2019-10-24 Lithium-sulfur secondary battery

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KR1020190131538A KR20200047365A (ko) 2018-10-26 2019-10-22 리튬-황 이차전지

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JP7378641B2 (ja) 2020-11-26 2023-11-13 エルジー エナジー ソリューション リミテッド リチウム‐硫黄電池用電解液及びこれを含むリチウム‐硫黄電池

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7378641B2 (ja) 2020-11-26 2023-11-13 エルジー エナジー ソリューション リミテッド リチウム‐硫黄電池用電解液及びこれを含むリチウム‐硫黄電池

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