WO2020060097A1 - Sulfur-carbon composite and lithium secondary battery comprising same - Google Patents

Sulfur-carbon composite and lithium secondary battery comprising same Download PDF

Info

Publication number
WO2020060097A1
WO2020060097A1 PCT/KR2019/011707 KR2019011707W WO2020060097A1 WO 2020060097 A1 WO2020060097 A1 WO 2020060097A1 KR 2019011707 W KR2019011707 W KR 2019011707W WO 2020060097 A1 WO2020060097 A1 WO 2020060097A1
Authority
WO
WIPO (PCT)
Prior art keywords
sulfur
carbon
carbon composite
conductive polymer
black
Prior art date
Application number
PCT/KR2019/011707
Other languages
French (fr)
Korean (ko)
Inventor
김봉수
손권남
Original Assignee
주식회사 엘지화학
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020190111292A external-priority patent/KR20200033737A/en
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to US17/043,897 priority Critical patent/US12027704B2/en
Priority to ES19863939T priority patent/ES2975985T3/en
Priority to CN201980031792.XA priority patent/CN112106236A/en
Priority to EP19863939.5A priority patent/EP3764440B1/en
Priority to PL19863939.5T priority patent/PL3764440T3/en
Priority to JP2021503690A priority patent/JP7084544B2/en
Publication of WO2020060097A1 publication Critical patent/WO2020060097A1/en
Priority to US18/731,673 priority patent/US20240332528A1/en

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/02—Preparation of sulfur; Purification
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/158—Carbon nanotubes
    • C01B32/168—After-treatment
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • 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
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • 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
    • 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 sulfur-carbon composite applicable to the positive electrode material of a lithium secondary battery and a lithium secondary battery comprising the sulfur-carbon composite.
  • lithium-sulfur secondary batteries use sulfur-based sulfur compounds having a sulfur-sulfur bond as a positive electrode active material, and carbon-based materials or alloys with lithium, in which alkali metals such as lithium or metal ions such as lithium ions are inserted and de-inserted It is a secondary battery using silicon or tin to form a negative electrode active material.
  • the sulfur-oxidation number of sulfur decreases as the sulfur-sulfur bond is cut off during the reduction reaction discharge, and the electrical energy is stored using an oxidation-reduction reaction in which the sulfur-sulfur bond is formed again as the oxidation number of sulfur increases during charging as the oxidation reaction And create.
  • the sulfur used as the positive electrode active material of the lithium-sulfur secondary battery has a theoretical energy density of 1675 mAh / g, and has a theoretical energy density about 5 times higher than that of the positive electrode active material used in the existing lithium secondary battery, resulting in high power and high energy. It is a battery capable of expressing density.
  • sulfur is attracting attention as an energy source for medium and large-sized devices such as electric vehicles as well as portable electronic devices because of its low cost, rich reserves, and easy supply and demand.
  • Sulfur is a non-conductor, which is mainly used in combination with a conductive material, carbon. As the sulfur content in the anode increases, the energy density increases, but since the amount of the conductive material decreases, electrochemical overvoltage increases, resulting in a loss of electromotive force. .
  • Jun Jin et al discloses a positive electrode of a lithium-sulfur secondary battery comprising a mesoporous sulfur-carbon composite coated with a conductive polymer polyaniline.
  • Guo-Chun Li. et al. ( ADVANCED ENERGY MATERIALS 2012, 2, pp. 1238-1245) also discloses a lithium-sulfur secondary battery positive electrode active material comprising a sulfur-carbon black composite coated with a conductive polymer polyaniline.
  • Non-Patent Document 1 Jun Jin et al ., SOLID STATE IONICS 262 (2014) pp.170-173
  • Non-Patent Document 2 Guo-Chun Li. et al. , ADVANCED ENERGY MATERIALS 2012, 2, pp. 1238-1245
  • the present inventors conducted a multifaceted study to solve the above problems, and introduced a conductive polymer into the sulfur-carbon composite, but lithium ions can pass through the surface of the sulfur-carbon composite using polyaniline nanofibers as the conductive polymer. It was confirmed that the conductivity of the sulfur-carbon composite was improved by coating in a form to be performed. In addition, it was confirmed that the sulfur-carbon composite coated with the polyaniline nanofibers has improved adsorption rate to polysulfide, and that lithium ions move smoothly between the coated polyaniline nanofibers, thereby improving battery performance.
  • an object of the present invention is to provide a sulfur-carbon composite having a conductive polymer coating layer having a form capable of moving lithium ions.
  • Another object of the present invention is to provide a lithium secondary battery comprising a sulfur-carbon composite formed with a conductive polymer coating layer having a form capable of moving lithium ions.
  • the present invention provides a sulfur-carbon composite comprising a network-type conductive polymer coating layer.
  • the conductive polymer is polyaniline, polypyrrole, polythiophene, poly (3,4-ethylenedioxythiophene), polyacetylene, poly It may be one or more selected from the group consisting of diacetylene, polythiophenevinylene, polyfluorene and derivatives thereof.
  • the shape of the conductive polymer may be at least one selected from the group consisting of nanofibers, nanowires, nanorods, and nanotubes.
  • the sulfur-carbon composite may include: sulfur particles having at least one carbon particle therein; And carbon particles located on part or all of the surface of the sulfur particles.
  • the weight ratio of sulfur and carbon may be 6: 4 to 9: 1.
  • the content of the conductive polymer may be 0.1 to 10% by weight based on the total weight of the sulfur-carbon composite containing the conductive polymer coating layer.
  • the sulfur is sulfur (S 8 ), Li 2 S n (n is a real number of n ⁇ 1.), Organic sulfur compound and carbon-sulfur polymer [(C 2 S x ) n , x is a real number of 2.5 to 50, n is a real number of n ⁇ 2].
  • the carbon is graphite (graphite), graphene (graphene), super P (Super P), carbon black, denka black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, carbon It may be one or more selected from the group consisting of nanofibers, carbon nanotubes, carbon nanowires, carbon nanorings, carbon fabrics, and fullerenes (C60).
  • the present invention also provides an anode comprising the sulfur-carbon composite.
  • the present invention also provides a lithium secondary battery comprising the sulfur-carbon composite.
  • the sulfur-carbon composite according to the present invention since a conductive polymer coating layer is introduced to adsorb polysulfide eluted from the positive electrode when applied to a lithium-sulfur secondary battery, as the polysulfide is dissolved in an electrolyte and moves to the negative electrode It is possible to prevent the phenomenon of reduced lifespan.
  • the sulfur-carbon composite may be improved in conductivity by introducing a conductive polymer coating layer.
  • the conductive polymer coating layer is formed of the conductive polymer nanofibers, a space in which lithium ions can move can be secured, so that the movement of lithium ions can be facilitated.
  • the sulfur-carbon composite including the conductive polymer coating layer formed by the conductive polymer nanofiber is applied to the positive electrode of a lithium-sulfur secondary battery, performance of the lithium-sulfur secondary battery may be improved.
  • FIG. 1 is a schematic view of a sulfur-carbon composite including a conductive polymer coating layer according to the present invention.
  • FIG. 2 is a graph showing a correlation between electric potential and current when a charging voltage is applied to an electrolyte solution to which aniline is added and an electrolyte solution to which aniline is not added according to Comparative Example 2.
  • 3A and 3B are scanning electron microscopy (SEM) photographs of polyaniline nanofibers synthesized in Preparation Example 1 and polyaniline nanofiber coating layers formed on the surface of the sulfur-carbon composite prepared in Example 1.
  • Example 4 is a graph showing the first discharge curve as a result of coin cell evaluation of the lithium-sulfur secondary batteries prepared in Example 1 and Comparative Examples 1 and 2, respectively.
  • the present invention relates to a sulfur-carbon composite comprising a conductive polymer coating layer.
  • FIG. 1 is a schematic view of a sulfur-carbon composite including a conductive polymer coating layer according to the present invention.
  • the sulfur-carbon composite 10 including the conductive polymer coating layer may have a conductive polymer coating layer 12 formed on the surface of the sulfur-carbon composite 11.
  • the conductive polymers constituting the conductive polymer coating layer 12 are polyaniline, polypyrrole, polythiophene, poly (3,4-ethylenedioxythiophene), polyacetylene, polydiacetylene, polythiophenevinylene, polyfullerene, and these. It may be one or more selected from the group consisting of derivatives, preferably the conductive polymer may be polyaniline.
  • the shape of the conductive polymer coating layer 12 may be a network type.
  • the network type means that the coating layer formed on the surface of the sulfur-carbon composite is not formed on the entire surface of the sulfur-carbon composite, but is formed in a net shape so that a part of the surface of the sulfur-carbon composite is exposed.
  • a space is formed in a portion where the surface of the sulfur-carbon composite is exposed, and thus lithium ions can freely move through the space.
  • the conductive polymer may have one or more nanostructure shapes selected from the group consisting of nanowires, nanorods, and nanotubes.
  • the conductive polymer may have a nanofiber shape, and in this case, it may be advantageous for forming a network-type coating layer.
  • the diameter of the nanofibers may be 10 nm to 1 ⁇ m, preferably 20 nm to 500 nm, more preferably 50 nm to 200 nm. If it is less than the above range, the effect of improving the conductivity of the sulfur-carbon composite may be negligible, and if it is above the above range, the space formed in the coating layer formed in a network form may be narrowed, and lithium ion migration may be difficult.
  • the content of the conductive polymer may be 0.1 to 10% by weight, preferably 0.5 to 7% by weight, more preferably 1 to 5% by weight based on the total weight of the sulfur-carbon composite including the conductive polymer coating layer. If it is less than the above range, the effect of improving the conductivity of the sulfur-carbon composite may be negligible, and if it is more than the above range, the performance of the battery may decrease when applied to the battery.
  • the sulfur-carbon composite 11 includes sulfur particles containing at least one carbon particle therein; And carbon particles located on part or all of the surface of the sulfur particles.
  • the sulfur-carbon composite 11 has a structure in which carbon particles are contained inside and outside of the sulfur particles, sulfur and carbon can be mixed in a uniform ratio, so that the conductive material, carbon, effectively imparts electron conductivity to sulfur. It has the advantage of being able to do it.
  • the sulfur is sulfur (S 8 ), Li 2 S n (n is a real number of n ⁇ 1), an organic sulfur compound and a carbon-sulfur polymer [(C 2 S x ) n , x is a real number of 2. to 50, n is a real number of n ⁇ 2] may be one or more selected from the group consisting of.
  • the carbon is graphite, graphene, super P, carbon black, denka black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, carbon nanofiber, carbon nanotube, carbon It may be one or more selected from the group consisting of nanowires, carbon nanorings, carbon fabrics, and fullerenes (C60).
  • the diameter of the sulfur-carbon composite 11 may be 5 to 100 ⁇ m, preferably 10 to 70 ⁇ m, and more preferably 15 to 60 ⁇ m.
  • the diameter of the sulfur-carbon composite 11 means the length of the longest axis in the cross section of the sulfur-carbon composite particles. If it is less than the above range, the surface area to be coated by the conductive polymer nanofiber is too large to coat all of the surface area, so that the effect of coating may not be exhibited. You can.
  • the weight ratio of sulfur and carbon may be 60:40 to 90:10, preferably 65:35 to 85:15, and more preferably 70:30 to 80:20. If the weight ratio of carbon to sulfur is less than the above range, conductivity may be lowered, and if it is above the above range, the amount of active material may be reduced and energy density may be lowered.
  • the present invention also relates to a method for producing a sulfur-carbon composite comprising a conductive polymer coating layer, wherein the method for producing a sulfur-carbon composite comprises: (S1) preparing a concentrated dispersion containing a conductive polymer; (S2) preparing a sulfur-carbon composite by mixing a sulfur powder and a carbon material; And (S3) mixing and drying the concentrated dispersion and a sulfur-carbon composite to form a conductive polymer coating layer on the sulfur-carbon composite.
  • step (S1) it is possible to prepare a concentrated dispersion containing a conductive polymer.
  • the conductive polymer may have a shape capable of forming a network-type coating layer. Specific types and shapes of the conductive polymer are as described above. Preferably, the conductive polymer may be polyaniline nanofibers.
  • the process of dispersing and filtering the conductive polymer in water may be repeated several times to prepare a concentrated dispersion containing the conductive polymer.
  • step (S2) sulfur and carbon may be mixed to prepare a sulfur-carbon composite.
  • sulfur and carbon are each in the form of particles, and the specific types and diameters of sulfur and carbon are as described above.
  • sulfur and carbon may be dispersed in an organic solvent, heated, and melted and mixed by a melt diffusion method to form a sulfur-carbon composite.
  • the organic solvent may be one or more selected from the group consisting of dimethyl sulfoxide, diethylene glycol methyl ethyl ether, ethylene glycol butyl ether, and 2-butoxyethyl acetate, but is not limited thereto.
  • a wide range of organic solvents that can be dispersed can be used.
  • the temperature at the time of heating may be more than the melting point of sulfur. That is, the temperature during heating may be 115.21 ° C or higher, preferably 130 to 200 ° C, and more preferably 150 to 200 ° C. If it is less than the above range, sulfur cannot be melted to form a sulfur-carbon composite. If it is more than the above range, the sulfur-carbon composite is denatured and the effect of improving the performance of the battery may be insignificant when applied as a cathode material for a lithium secondary battery.
  • step (S3) a concentrated dispersion containing the conductive polymer obtained in the step (S1), a sulfur-carbon composite obtained in the step (S2) and a solvent are mixed and dried to form a conductive polymer coating layer on the sulfur-carbon composite can do.
  • the solvent is a solvent having good affinity with the sulfur-carbon complex, and may be one or more selected from the group consisting of water, ethanol, acetone, dichloromethane and 1-methyl-2-pyrrolidone.
  • the present invention also relates to a lithium secondary battery comprising a sulfur-carbon composite as described above.
  • the sulfur-carbon composite may be preferably included as a positive electrode active material.
  • the lithium secondary battery according to the present invention may include a positive electrode, a negative electrode, a separator interposed therebetween, and an electrolyte.
  • the positive electrode of the lithium secondary battery may include a positive electrode current collector and a positive electrode mixture layer having a positive electrode active material formed on the positive electrode current collector.
  • the positive electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. Carbon, nickel, titanium, silver or the like may be used.
  • the positive electrode current collector may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabrics, etc. with fine irregularities formed on the surface so as to increase adhesion with the positive electrode active material.
  • the negative electrode of the lithium secondary battery may include a negative electrode current collector and a negative electrode mixture layer having a negative electrode active material formed on the negative electrode current collector.
  • a carbon material lithium metal, silicon, or tin, which can normally occlude and release lithium ions
  • a carbon material can be used, and both low-crystalline carbon and high-crystalline carbon may be used as the carbon material.
  • Soft carbon and hard carbon are typical examples of low crystalline carbon, and natural graphite, Kish graphite, pyrolytic carbon, and liquid crystal pitch-based carbon fibers are examples of high crystalline carbon.
  • High-temperature calcined carbon such as (mesophase pitch based carbon fiber), meso-carbon microbeads, Mesophase pitches, and petroleum or coal tar pitch derived cokes are typical examples.
  • the negative electrode may include a binder, and as a binder, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (polyvinylidenefluoride), polyacrylonitrile (polyacrylonitrile), Various types of binder polymers, such as polymethylmethacrylate, can be used.
  • PVDF-co-HFP vinylidene fluoride-hexafluoropropylene copolymer
  • PVDF-co-HFP vinylidene fluoride-hexafluoropropylene copolymer
  • polyvinylidene fluoride polyvinylidenefluoride
  • polyacrylonitrile polyacrylonitrile
  • Various types of binder polymers, such as polymethylmethacrylate can be used.
  • the negative electrode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel. Carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloy, or the like may be used.
  • the cathode current collector like the anode current collector, various forms such as a film, sheet, foil, net, porous body, foam, and non-woven fabric having fine irregularities on the surface may be used.
  • the positive electrode mixture layer or the negative electrode mixture layer may further include a binder resin, a conductive material, a filler, and other additives.
  • the binder resin is used for bonding the electrode active material and the conductive material and bonding to the current collector.
  • a binder resin examples include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetra And fluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, and various copolymers thereof.
  • PVDF polyvinylidene fluoride
  • CMC carboxymethyl cellulose
  • EPDM ethylene-propylene-diene polymer
  • sulfonated-EPDM styrene-butadiene rubber
  • fluorine rubber and various copolymers thereof.
  • the conductive material is used to further improve the conductivity of the electrode active material.
  • the conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery.
  • graphite such as natural graphite or artificial graphite
  • Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer 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
  • Polyphenylene derivatives and the like can be used.
  • the filler is selectively used as a component that suppresses the expansion of the electrode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery.
  • olefinic polymers such as polyethylene and polypropylene
  • Fibrous materials such as glass fibers and carbon fibers are used.
  • the separation membrane may be made of a porous substrate, and the porous substrate may be any porous substrate commonly used in electrochemical devices, for example, a polyolefin-based porous membrane (membrane) or non-woven fabric. It can be used, but is not particularly limited thereto.
  • polyolefin-based porous membrane examples include polyolefin-based polymers such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene, polypropylene, polybutylene, and polypentene, respectively, alone or as a mixture of these.
  • polyolefin-based polymers such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene, polypropylene, polybutylene, and polypentene, respectively, alone or as a mixture of these.
  • One membrane is mentioned.
  • the nonwoven fabric includes, in addition to the polyolefin nonwoven fabric, for example, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate ), Polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, and polyethylene naphthalene, respectively, or And nonwoven fabrics formed of polymers in which these are mixed.
  • the structure of the nonwoven fabric may be a spunbond nonwoven fabric composed of long fibers or a melt blown nonwoven fabric.
  • the thickness of the porous substrate is not particularly limited, but is 1 ⁇ m to 100 ⁇ m, or 5 ⁇ m to 50 ⁇ m.
  • the size and pores of the pores present in the porous substrate are also not particularly limited, but may be 0.001 ⁇ m to 50 ⁇ m and 10% to 95%, respectively.
  • the electrolyte solution may be a non-aqueous electrolyte solution, and the electrolyte salt contained in the non-aqueous electrolyte solution is a lithium salt.
  • the lithium salt may be used without limitation to those commonly used in electrolytes for lithium secondary batteries.
  • the lithium salt is LiFSI, LiPF 6 , LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiPF 6 , LiAlCl 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, chloroborane lithium, and 4-phenyl lithium borate.
  • organic solvent included in the above-mentioned non-aqueous electrolyte those commonly used in electrolytes for lithium secondary batteries can be used without limitation, for example, ether, ester, amide, linear carbonate, cyclic carbonate, etc. alone or in combination of two or more, respectively. It can be used by mixing. Among them, a cyclic carbonate, a linear carbonate, or a carbonate compound that is a slurry thereof may be included.
  • cyclic carbonate compound examples include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-Pentylene carbonate, vinylene carbonate, vinyl ethylene carbonate and any one selected from the group consisting of halides, or a slurry of two or more of them.
  • halides include, but are not limited to, fluoroethylene carbonate (FEC).
  • linear carbonate compound may be any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate, or Of these, two or more types of slurries may be typically used, but are not limited thereto.
  • ethylene carbonate and propylene carbonate which are cyclic carbonates, are high-viscosity organic solvents and have higher dielectric constants, so that lithium salts in the electrolyte can be better dissociated, such as dimethyl carbonate and diethyl carbonate.
  • a low-viscosity, low-permittivity linear carbonate is mixed and used in an appropriate ratio, an electrolyte having a higher electrical conductivity can be produced.
  • any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether and ethylpropyl ether, or a slurry of two or more of them may be used. , But is not limited thereto.
  • esters of the organic solvent include methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, ⁇ -valerolactone, ⁇ -caprolactone, Any one selected from the group consisting of ⁇ -valerolactone and ⁇ -caprolactone or a slurry of two or more of them may be used, but is not limited thereto.
  • the injection of the non-aqueous electrolyte may be performed at an appropriate step in the manufacturing process of the electrochemical device, depending on the manufacturing process of the final product and the required physical properties. That is, it can be applied before the electrochemical device assembly or at the final stage of the electrochemical device assembly.
  • a lamination, stacking, and folding process of a separator and an electrode may be performed in addition to winding, which is a general process.
  • the shape of the battery case is not particularly limited, and may be various shapes such as a cylindrical shape, a stacked shape, a square shape, a pouch shape, or a coin shape.
  • the structure and manufacturing method of these batteries are well known in the art, so detailed descriptions thereof are omitted.
  • the lithium secondary battery may be classified into various batteries such as a lithium-sulfur secondary battery, a lithium-air battery, a lithium-oxide battery, and a lithium solid-state battery according to the anode / cathode material used.
  • the present invention also provides a battery module including the lithium secondary battery as a unit cell.
  • the battery module can be used as a power source for medium to large-sized devices that require high temperature stability, long cycle characteristics, and high capacity characteristics.
  • Examples of the medium-to-large-sized device include a power tool that is powered by an omniscient motor and moves; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like; Electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); Electric golf carts; A power storage system, and the like, but is not limited thereto.
  • Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like
  • Electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters)
  • Electric golf carts A power storage system, and the like, but is not limited thereto.
  • the sulfur-carbon composite according to the present invention can be applied to a positive electrode of a lithium-sulfur secondary battery, among lithium secondary batteries.
  • the lithium-sulfur secondary battery may be a battery including the sulfur-carbon composite as a positive electrode active material.
  • the sulfur-carbon composite can exhibit high ionic conductivity by securing the path of lithium ions to the inside of the pores, and acts as a sulfur carrier to increase the reactivity with the positive electrode active material, sulfur, and the capacity and life of the lithium-sulfur secondary battery The characteristics can be improved at the same time.
  • Aniline was dissolved in 1M HCl to prepare 100 ml of a 0.32 M aniline solution.
  • Ammonium persulfate was dissolved in 1M HCl to prepare 100 ml of a 0.08M ammonium persulfate solution.
  • the aniline solution and ammonium persulfate solution were mixed to obtain a mixed solution.
  • the initial reaction was performed while rapidly mixing at room temperature, followed by additional reaction for 10 hours in the state of the mixed solution to prepare a polyaniline nanofiber dispersion.
  • the polyaniline nanofiber dispersion obtained in Preparation Example 1 was filtered to filter out polyaniline nanofibers excluding the remaining reactants, and after being redispersed and re-filtered in water several times to neutralize the pH to 6 or higher, polyaniline nanofibers having a concentration of 5% A concentrated dispersion was obtained.
  • a sulfur-carbon composite was prepared by mixing carbon nanotubes and sulfur in a weight ratio of 25:75 and supporting sulfur on carbon through a melt diffusion method at 155 ° C.
  • the polyaniline nanofiber concentrated dispersion obtained in (1), the sulfur-carbon composite obtained in (2) and ethanol were mixed in a weight ratio of 1: 1.
  • the mixed solution obtained after mixing was dried to remove the solvent, thereby preparing a sulfur-carbon composite having a polyaniline nanofiber coating layer.
  • the polyaniline contained in the sulfur-carbon composite on which the polyaniline nanofiber coating layer is formed is 5% by weight.
  • anode mixture layer including the sulfur-carbon composite was formed on one surface of the Al current collector to prepare an anode.
  • the positive electrode mixture layer is a mixture of polyacrylic acid (PAA) and carbon black as a weight ratio of 88: 7: 5 as the sulfur-carbon composite and a binder, and then a slurry dispersed in water is coated on one surface of the Al current collector. And dried and dried.
  • PAA polyacrylic acid
  • carbon black as a weight ratio of 88: 7: 5 as the sulfur-carbon composite and a binder
  • a lithium-sulfur secondary battery in the form of a coin cell was prepared using an electrolyte and a polyolefin separator.
  • a sulfur-carbon composite was prepared in the same manner as in Example 1, but the polyaniline nanofiber coating layer was not formed.
  • FIG. 2 is a graph showing a correlation between electric potential and current when a charging voltage is applied to an electrolyte solution to which aniline is added and an electrolyte solution to which aniline is not added according to Comparative Example 2.
  • 3A and 3B are SEM photographs of the polyaniline nanofiber coating layer formed on the surfaces of the polyaniline nanofibers synthesized in Preparation Example 1 and the sulfur-carbon composite prepared in Example 1, respectively.
  • a coating layer having a network shape was formed by forming a coating layer on the surface of the sulfur-carbon composite using polyaniline nanofibers.
  • FIG. 4 is a graph showing the first discharge curve as a result of coin cell evaluation of the lithium-sulfur secondary batteries prepared in Example 1, Comparative Examples 1 and 2, respectively, and FIG. 5 is prepared in Example 1, Comparative Examples 1 and 2, respectively. Showing a cycle-discharge curve of a lithium-sulfur secondary battery.
  • Comparative Example 2 although the overvoltage was partially improved compared to Comparative Example 1, a polyaniline coating layer in the form of a film was formed, so that the voltage at the discharge end was reduced, so it did not exhibit sufficient capacity, and it was confirmed that the performance was poor compared to Example 1 Did.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Nanotechnology (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The present invention relates to a sulfur-carbon composite and a lithium secondary battery comprising same. More specifically, a network-shaped coating layer comprising a conductive polymer is formed on the surface of the sulfur-carbon composite, and thus the conductivity of the sulfur-carbon composite is enhanced and also, lithium ions move freely, and accordingly, when applied to lithium secondary batteries, the sulfur-carbon composite can enhance the performance of batteries.

Description

황-탄소 복합체 및 이를 포함하는 리튬 이차전지Sulfur-carbon composite and lithium secondary battery comprising the same
본 출원은 2018년 9월 20일자 한국 특허 출원 제10-2018-0112636호 및 2019년 9월 9일자 한국 특허 출원 제10-2019-0111292호에 기초한 우선권의 이익을 주장하며, 해당 한국 특허 출원의 문헌에 개시된 모든 내용은 본 명세서의 일부로서 포함한다.This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0112636 on September 20, 2018 and Korean Patent Application No. 10-2019-0111292 on September 9, 2019. All content disclosed in the literature is incorporated as part of this specification.
본 발명은 리튬 이차전지의 양극재로 적용 가능한 황-탄소 복합체 및 이를 포함하는 리튬 이차전지에 관한 것이다.The present invention relates to a sulfur-carbon composite applicable to the positive electrode material of a lithium secondary battery and a lithium secondary battery comprising the sulfur-carbon composite.
최근 전자 기기 분야와 전기 자동차 분야의 급속한 발전에 따라 이차전지의 수요가 증가하고 있다. 특히, 휴대용 전자 기기의 소형화 및 경량화 추세에 따라, 그에 부응할 수 있는 고 에너지 밀도를 갖는 이차전지에 대한 요구가 커지고 있다.2. Description of the Related Art With the rapid development of the electronic device field and the electric vehicle field, the demand for secondary batteries is increasing. Particularly, according to the trend of miniaturization and weight reduction of portable electronic devices, there is a growing demand for secondary batteries having high energy densities that can respond thereto.
이차전지 중 리튬-황 이차전지는 황-황 결합을 갖는 황계 화합물을 양극 활물질로 사용하고, 리튬과 같은 알칼리 금속 또는 리튬 이온과 같은 금속 이온의 삽입 및 탈삽입이 일어나는 탄소계 물질 또는 리튬과 합금을 형성하는 실리콘이나 주석 등을 음극 활물질로 사용하는 이차전지다. 구체적으로, 환원 반응인 방전시 황-황 결합이 끊어지면서 황의 산화수가 감소하고, 산화 반응인 충전시 황의 산화수가 증가하면서 황-황 결합이 다시 형성되는 산화-환원 반응을 이용하여 전기적 에너지를 저장하고 생성한다.Among the secondary batteries, lithium-sulfur secondary batteries use sulfur-based sulfur compounds having a sulfur-sulfur bond as a positive electrode active material, and carbon-based materials or alloys with lithium, in which alkali metals such as lithium or metal ions such as lithium ions are inserted and de-inserted It is a secondary battery using silicon or tin to form a negative electrode active material. Specifically, the sulfur-oxidation number of sulfur decreases as the sulfur-sulfur bond is cut off during the reduction reaction discharge, and the electrical energy is stored using an oxidation-reduction reaction in which the sulfur-sulfur bond is formed again as the oxidation number of sulfur increases during charging as the oxidation reaction And create.
특히, 리튬-황 이차전지의 양극 활물질로 사용되는 황은 이론 에너지 밀도가 1675 mAh/g으로, 기존의 리튬 이차전지에서 사용되는 양극 활물질에 비해 5배 정도 높은 이론 에너지 밀도를 가지고 있어 고출력 및 고에너지 밀도의 발현이 가능한 전지이다. 이에 더해서 황은 값이 저렴하고 매장량이 풍부해 수급이 용이하며 환경친화적이라는 이점 때문에 휴대용 전자 기기뿐만 아니라 전기 자동차와 같은 중대형 장치의 에너지원으로 주목 받고 있다.In particular, the sulfur used as the positive electrode active material of the lithium-sulfur secondary battery has a theoretical energy density of 1675 mAh / g, and has a theoretical energy density about 5 times higher than that of the positive electrode active material used in the existing lithium secondary battery, resulting in high power and high energy. It is a battery capable of expressing density. In addition, sulfur is attracting attention as an energy source for medium and large-sized devices such as electric vehicles as well as portable electronic devices because of its low cost, rich reserves, and easy supply and demand.
황은 부도체로서, 전도성 물질인 탄소와 복합체를 이루어 주로 사용되는데, 양극 내에 황 함량이 높을수록 에너지 밀도가 증가하지만, 전도성 소재의 양이 감소하므로, 전기화학적 과전압이 증가하여 기전력이 상실되는 문제점이 있었다.Sulfur is a non-conductor, which is mainly used in combination with a conductive material, carbon. As the sulfur content in the anode increases, the energy density increases, but since the amount of the conductive material decreases, electrochemical overvoltage increases, resulting in a loss of electromotive force. .
이와 같은 리튬-황 이차전지의 문제점을 해결하고자 폴리 설파이드를 흡착하는 소재를 양극재에 코팅하거나, 분리막 또는 음극과 같은 전지 내의 구성품에 도입하는 기술이 제안되었다. 또한, 전도성 고분자를 양극재에 코팅하는 연구 결과도 보고된 바 있다. In order to solve the problem of the lithium-sulfur secondary battery, a technique has been proposed in which a material adsorbing polysulfide is coated on a positive electrode material or introduced into a component in a battery such as a separator or a negative electrode. In addition, research results of coating a conductive polymer on a cathode material have also been reported.
일례로, Jun Jin et al. (SOLID STATE IONICS 262(2014) pp.170-173) 는 전도성 고분자인 폴리아닐린으로 코팅된 메조포러스 황-탄소 복합체를 포함하는 리튬-황 이차전지의 양극을 개시하고 있다.As an example, Jun Jin et al . (SOLID STATE IONICS 262 (2014) pp.170-173) discloses a positive electrode of a lithium-sulfur secondary battery comprising a mesoporous sulfur-carbon composite coated with a conductive polymer polyaniline.
또한, Guo-Chun Li. et al. (ADVANCED ENERGY MATERIALS 2012, 2, pp. 1238-1245) 역시 전도성 고분자인 폴리아닐린으로 코팅된 황-탄소블랙 복합체를 포함하는 리튬-황 이차전지 양극 활물질을 개시하고 있다.In addition, Guo-Chun Li. et al. ( ADVANCED ENERGY MATERIALS 2012, 2, pp. 1238-1245) also discloses a lithium-sulfur secondary battery positive electrode active material comprising a sulfur-carbon black composite coated with a conductive polymer polyaniline.
그러나, 이들 문헌들에서 제시하는 황-탄소 복합체의 경우 폴리아닐린이 박막형으로 코팅되어 있어, 리튬 이온의 이동이 어려워지는 문제가 있다.However, in the case of the sulfur-carbon composite presented in these documents, polyaniline is coated in a thin film form, and thus there is a problem that the movement of lithium ions becomes difficult.
따라서, 황-탄소 복합체의 전도성을 향상시키면서도 리튬 이온의 이동을 원활히 할 수 있는 기술의 개발이 시급한 실정이다.Accordingly, there is an urgent need to develop a technology capable of smoothly moving lithium ions while improving the conductivity of the sulfur-carbon composite.
[비특허문헌][Non-patent literature]
(비특허문헌 1) Jun Jin et al., SOLID STATE IONICS 262(2014) pp.170-173 (Non-Patent Document 1) Jun Jin et al ., SOLID STATE IONICS 262 (2014) pp.170-173
(비특허문헌 2) Guo-Chun Li. et al., ADVANCED ENERGY MATERIALS 2012, 2, pp. 1238-1245(Non-Patent Document 2) Guo-Chun Li. et al. , ADVANCED ENERGY MATERIALS 2012, 2, pp. 1238-1245
본 발명자들은 상기 문제점을 해결하기 위해 다각적으로 연구를 수행한 결과, 황-탄소 복합체에 전도성 고분자를 도입하되, 전도성 고분자로서 폴리아닐린 나노섬유를 이용하여 상기 황-탄소 복합체의 표면을 리튬 이온이 통과 가능하도록 하는 형태로 코팅함으로써, 황-탄소 복합체의 전도성이 개선되는 것을 확인하였다. 또한, 상기 폴리아닐린 나노섬유로 코팅된 황-탄소 복합체는 폴리 설파이드에 대한 흡착률이 향상되며, 상기 코팅된 폴리아닐린 나노섬유 사이로 리튬 이온의 이동이 원활하게 이루어져 전지의 성능이 향상된다는 것을 확인하였다.The present inventors conducted a multifaceted study to solve the above problems, and introduced a conductive polymer into the sulfur-carbon composite, but lithium ions can pass through the surface of the sulfur-carbon composite using polyaniline nanofibers as the conductive polymer. It was confirmed that the conductivity of the sulfur-carbon composite was improved by coating in a form to be performed. In addition, it was confirmed that the sulfur-carbon composite coated with the polyaniline nanofibers has improved adsorption rate to polysulfide, and that lithium ions move smoothly between the coated polyaniline nanofibers, thereby improving battery performance.
따라서, 본 발명의 목적은 리튬 이온의 이동이 가능한 형태를 가지는 전도성 고분자 코팅층이 형성된 황-탄소 복합체를 제공하는 것이다.Accordingly, an object of the present invention is to provide a sulfur-carbon composite having a conductive polymer coating layer having a form capable of moving lithium ions.
본 발명의 다른 목적은 리튬 이온의 이동이 가능한 형태를 가지는 전도성 고분자 코팅층이 형성된 황-탄소 복합체를 포함하는 리튬 이차전지를 제공하는 것이다.Another object of the present invention is to provide a lithium secondary battery comprising a sulfur-carbon composite formed with a conductive polymer coating layer having a form capable of moving lithium ions.
상기 목적을 달성하기 위해, 본 발명은, 네트워크형 전도성 고분자 코팅층을 포함하는 황-탄소 복합체을 제공한다.In order to achieve the above object, the present invention provides a sulfur-carbon composite comprising a network-type conductive polymer coating layer.
상기 전도성 고분자는 폴리아닐린(polyaniline), 폴리피롤(polypyrrole), 폴리티오펜(polythiophene), 폴리(3,4-에틸렌디옥시티오펜)(poly(3,4-ethylenedioxythiophene)), 폴리아세틸렌(polyacetylene), 폴리디아세틸렌(polydiacetylene), 폴리티오펜비닐렌(poly(thiophenevinylene)), 폴리플러렌(polyfluorene) 및 이들의 유도체로 이루어진 군에서 선택되는 1종 이상일 수 있다.The conductive polymer is polyaniline, polypyrrole, polythiophene, poly (3,4-ethylenedioxythiophene), polyacetylene, poly It may be one or more selected from the group consisting of diacetylene, polythiophenevinylene, polyfluorene and derivatives thereof.
상기 전도성 고분자의 형상은 나노섬유, 나노와이어, 나노로드 및 나노튜브로 이루어진 군에서 선택되는 1종 이상일 수 있다.The shape of the conductive polymer may be at least one selected from the group consisting of nanofibers, nanowires, nanorods, and nanotubes.
상기 황-탄소 복합체는, 내부에 적어도 하나의 탄소 입자가 포함된 황 입자; 및 상기 황 입자 표면의 일부 또는 전부에 위치하는 탄소 입자;를 포함하는 것일 수 있다.The sulfur-carbon composite may include: sulfur particles having at least one carbon particle therein; And carbon particles located on part or all of the surface of the sulfur particles.
상기 황과 탄소의 중량비는 6:4 내지 9:1일 수 있다.The weight ratio of sulfur and carbon may be 6: 4 to 9: 1.
상기 전도성 고분자의 함량은 상기 전도성 고분자 코팅층을 포함하는 황-탄소 복합체 전체 중량을 기준으로 0.1 내지 10 중량%일 수 있다.The content of the conductive polymer may be 0.1 to 10% by weight based on the total weight of the sulfur-carbon composite containing the conductive polymer coating layer.
상기 황은 황(S8), Li2Sn(n은 n≥1의 실수임.), 유기 황 화합물 및 탄소-황 폴리머[(C2Sx)n, x는 2.5 내지 50의 실수임, n은 n≥2인 실수임]로 이루어진 군에서 선택되는 1종 이상일 수 있다.The sulfur is sulfur (S 8 ), Li 2 S n (n is a real number of n ≧ 1.), Organic sulfur compound and carbon-sulfur polymer [(C 2 S x ) n , x is a real number of 2.5 to 50, n is a real number of n≥2].
상기 탄소는 그라파이트(graphite), 그래핀(graphene), 수퍼 P(Super P), 카본 블랙, 덴카 블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼네이스 블랙, 램프 블랙, 서머 블랙, 탄소 섬유, 탄소 나노 섬유, 탄소나노튜브, 탄소 나노 와이어, 탄소 나노 링, 탄소 직물 및 플러렌(C60)로 이루어진 군에서 선택되는 1종 이상일 수 있다.The carbon is graphite (graphite), graphene (graphene), super P (Super P), carbon black, denka black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, carbon It may be one or more selected from the group consisting of nanofibers, carbon nanotubes, carbon nanowires, carbon nanorings, carbon fabrics, and fullerenes (C60).
본 발명은 또한, 상기 황-탄소 복합체를 포함하는 양극을 제공한다.The present invention also provides an anode comprising the sulfur-carbon composite.
본 발명은 또한, 상기 황-탄소 복합체를 포함하는 리튬 이차전지를 제공한다.The present invention also provides a lithium secondary battery comprising the sulfur-carbon composite.
본 발명에 따른 황-탄소 복합체에 의하면, 전도성 고분자 코팅층이 도입되어 리튬-황 이차전지에 적용시 양극에서 용출되는 폴리 설파이드를 흡착할 수 있으므로, 상기 폴리 설파이드가 전해액에 용해되어 음극으로 이동함에 따라 발생하는 수명 감소 현상을 방지할 수 있다.According to the sulfur-carbon composite according to the present invention, since a conductive polymer coating layer is introduced to adsorb polysulfide eluted from the positive electrode when applied to a lithium-sulfur secondary battery, as the polysulfide is dissolved in an electrolyte and moves to the negative electrode It is possible to prevent the phenomenon of reduced lifespan.
또한, 상기 황-탄소 복합체에 폴리 설파이드가 흡착될 경우 탄소와 함께 도전 구조를 구성하므로, 황의 이용율을 개선할 수 있다.In addition, when polysulfide is adsorbed on the sulfur-carbon composite, since a conductive structure is formed together with carbon, the utilization rate of sulfur can be improved.
또한, 상기 황-탄소 복합체는, 전도성 고분자 코팅층이 도입되어 전도성이 개선될 수 있다.In addition, the sulfur-carbon composite may be improved in conductivity by introducing a conductive polymer coating layer.
또한, 상기 전도성 고분자 코팅층이 형성된 황-탄소 복합체에서, 상기 전도성 고분자 코팅층 전도성 고분자 나노섬유에 의해 형성되어, 리튬 이온이 이동할 수 있는 공간을 확보할 수 있으므로, 리튬 이온의 이동을 원활하게 할 수 있다.In addition, in the sulfur-carbon composite on which the conductive polymer coating layer is formed, since the conductive polymer coating layer is formed of the conductive polymer nanofibers, a space in which lithium ions can move can be secured, so that the movement of lithium ions can be facilitated. .
또한, 상기 전도성 고분자 나노섬유에 의해 형성된 전도성 고분자 코팅층을 포함하는 황-탄소 복합체를 리튬-황 이차전지의 양극에 적용할 경우, 리튬-황 이차전지의 성능을 향상시킬 수 있다.In addition, when the sulfur-carbon composite including the conductive polymer coating layer formed by the conductive polymer nanofiber is applied to the positive electrode of a lithium-sulfur secondary battery, performance of the lithium-sulfur secondary battery may be improved.
도 1은 본 발명에 따른, 전도성 고분자 코팅층을 포함하는 황-탄소 복합체의 모식도이다.1 is a schematic view of a sulfur-carbon composite including a conductive polymer coating layer according to the present invention.
도 2는 비교예 2에 따라 아닐린을 첨가한 전해액 및 아닐린을 미첨가한 전해액에 충전 전압을 인가할 경우의 전위와 전류의 상관관계를 나타낸 그래프이다.FIG. 2 is a graph showing a correlation between electric potential and current when a charging voltage is applied to an electrolyte solution to which aniline is added and an electrolyte solution to which aniline is not added according to Comparative Example 2.
도 3a 및 3b는 각각 제조예 1에서 합성된 폴리아닐린 나노섬유 및 실시예 1에서 제조된 황-탄소 복합체의 표면에 형성된 폴리아닐린 나노섬유 코팅층에 대한 SEM(Scanning Electron Microscopy) 사진이다.3A and 3B are scanning electron microscopy (SEM) photographs of polyaniline nanofibers synthesized in Preparation Example 1 and polyaniline nanofiber coating layers formed on the surface of the sulfur-carbon composite prepared in Example 1.
도 4는 실시예 1, 비교예 1 및 2에서 각각 제조된 리튬-황 이차전지의 코인셀 평가 결과로서 첫 방전곡선을 나타낸 그래프이다.4 is a graph showing the first discharge curve as a result of coin cell evaluation of the lithium-sulfur secondary batteries prepared in Example 1 and Comparative Examples 1 and 2, respectively.
도 5는 실시예 1, 비교예 1 및 2에서 각각 제조된 리튬-황 이차전지의 사이클-방전용량 곡선을 도시한 그래프이다.5 is a graph showing cycle-discharge curves of lithium-sulfur secondary batteries prepared in Examples 1 and 1 and 2, respectively.
이하, 본 발명에 대한 이해를 돕기 위하여 본 발명을 더욱 상세하게 설명한다.Hereinafter, the present invention will be described in more detail to aid understanding of the present invention.
본 명세서 및 청구범위에서 사용된 용어나 단어는 통상적이거나 사전적인 의미로 한정해서 해석되어서는 아니 되며, 발명자는 그 자신의 발명을 가장 최선의 방법으로 설명하기 위해 용어의 개념을 적절하게 정의할 수 있다는 원칙에 입각하여 본 발명의 기술적 사상에 부합하는 의미와 개념으로 해석되어야만 한다.The terms or words used in the present specification and claims should not be interpreted as being limited to ordinary or lexical meanings, and the inventor can appropriately define the concept of terms in order to best describe his or her invention. Based on the principle that it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.
황-탄소 복합체Sulfur-carbon complex
본 발명은 전도성 고분자 코팅층을 포함하는 황-탄소 복합체에 관한 것이다.The present invention relates to a sulfur-carbon composite comprising a conductive polymer coating layer.
도 1은 본 발명에 따른, 전도성 고분자 코팅층을 포함하는 황-탄소 복합체의 모식도이다.1 is a schematic view of a sulfur-carbon composite including a conductive polymer coating layer according to the present invention.
도 1을 참조하면, 전도성 고분자 코팅층을 포함하는 황-탄소 복합체(10)는 황-탄소 복합체(11)의 표면에 전도성 고분자 코팅층(12)이 형성된 것일 수 있다. Referring to FIG. 1, the sulfur-carbon composite 10 including the conductive polymer coating layer may have a conductive polymer coating layer 12 formed on the surface of the sulfur-carbon composite 11.
상기 전도성 고분자 코팅층(12)을 이루는 전도성 고분자는 폴리아닐린, 폴리피롤, 폴리티오펜, 폴리(3,4-에틸렌디옥시티오펜), 폴리아세틸렌, 폴리디아세틸렌, 폴리티오펜비닐렌, 폴리플러렌 및 이들의 유도체로 이루어진 군에서 선택되는 1종 이상일 수 있으며, 바람직하게는 상기 전도성 고분자는 폴리아닐린일 수 있다.The conductive polymers constituting the conductive polymer coating layer 12 are polyaniline, polypyrrole, polythiophene, poly (3,4-ethylenedioxythiophene), polyacetylene, polydiacetylene, polythiophenevinylene, polyfullerene, and these. It may be one or more selected from the group consisting of derivatives, preferably the conductive polymer may be polyaniline.
또한, 상기 전도성 고분자 코팅층(12)의 형상은 네트워크형일 수 있다. 이때, 네트워크형이란 황-탄소 복합체의 표면에 형성된 코팅층이 상기 황-탄소 복합체의 표면 전체에 형성된 것이 아니라, 황-탄소 복합체의 표면 일부가 노출될 수 있도록 그물 형상으로 형성된 것을 의미한다. 상기 네트워크형의 전도성 고분자 코팅층(12)에는 상기 황-탄소 복합체의 표면 일부가 노출된 부분에 공간이 형성되어 있어,상기 공간을 통해 리튬 이온이 자유롭게 이동할 수 있는 장점이 있다.In addition, the shape of the conductive polymer coating layer 12 may be a network type. In this case, the network type means that the coating layer formed on the surface of the sulfur-carbon composite is not formed on the entire surface of the sulfur-carbon composite, but is formed in a net shape so that a part of the surface of the sulfur-carbon composite is exposed. In the network-type conductive polymer coating layer 12, a space is formed in a portion where the surface of the sulfur-carbon composite is exposed, and thus lithium ions can freely move through the space.
이와 같이 상기 전도성 고분자 코팅층이 네트워크형으로 형성되도록 하기 위해서는, 전도성 고분자가 나노와이어, 나노로드 및 나노튜브로 이루어진 군에서 선택되는 1종 이상의 나노 구조체 형상을 가지는 것일 수 있다. 바람직하게는 상기 전도성 고분자가 나노섬유 형상일 수 있으며, 이 경우 네트워크형 코팅층 형성에 유리할 수 있다.In order to form the conductive polymer coating layer in this way, the conductive polymer may have one or more nanostructure shapes selected from the group consisting of nanowires, nanorods, and nanotubes. Preferably, the conductive polymer may have a nanofiber shape, and in this case, it may be advantageous for forming a network-type coating layer.
또한, 상기 전도성 고분자가 나노섬유 형상일 경우, 상기 나노섬유의 직경은 10 nm 내지 1 ㎛, 바람직하게는 20 nm 내지 500 nm, 보다 바람직하게는 50 nm 내지 200 nm 일 수 있다. 상기 범위 미만이면 황-탄소 복합체의 전도성을 개선시키는 효과가 미미할 수 있으며, 상기 범위 초과이면 네트워크형으로 형성되는 코팅층에 형성되는 공간이 협소해져 리튬 이온의 이동이 어려울 수 있다.In addition, when the conductive polymer is in the form of nanofibers, the diameter of the nanofibers may be 10 nm to 1 μm, preferably 20 nm to 500 nm, more preferably 50 nm to 200 nm. If it is less than the above range, the effect of improving the conductivity of the sulfur-carbon composite may be negligible, and if it is above the above range, the space formed in the coating layer formed in a network form may be narrowed, and lithium ion migration may be difficult.
상기 전도성 고분자의 함량은 전도성 고분자 코팅층을 포함하는 황-탄소 복합체 전체 중량을 기준으로 0.1 내지 10 중량%, 바람직하게는 0.5 내지 7 중량%, 보다 바람직하게는 1 내지 5 중량%일 수 있다. 상기 범위 미만이면 황-탄소 복합체의 전도성 개선 효과가 미미할 수 있고, 상기 범위 초과이면 전지에 적용시 전지의 성능이 저하될 수 있다.The content of the conductive polymer may be 0.1 to 10% by weight, preferably 0.5 to 7% by weight, more preferably 1 to 5% by weight based on the total weight of the sulfur-carbon composite including the conductive polymer coating layer. If it is less than the above range, the effect of improving the conductivity of the sulfur-carbon composite may be negligible, and if it is more than the above range, the performance of the battery may decrease when applied to the battery.
상기 황-탄소 복합체(11)는 내부에 적어도 하나의 탄소 입자가 포함된 황 입자; 및 상기 황 입자 표면의 일부 또는 전부에 위치하는 탄소 입자;를 포함하는 것일 수 있다.The sulfur-carbon composite 11 includes sulfur particles containing at least one carbon particle therein; And carbon particles located on part or all of the surface of the sulfur particles.
또한, 상기 황-탄소 복합체(11)는 황 입자의 내부와 외부에 탄소 입자들이 포함되는 구조이므로 황과 탄소가 균일한 비율로 혼합될 수 있어, 도전재인 탄소가 황에 대해서 전자 전도성을 효과적으로 부여해줄 수 있다는 장점이 있다.In addition, since the sulfur-carbon composite 11 has a structure in which carbon particles are contained inside and outside of the sulfur particles, sulfur and carbon can be mixed in a uniform ratio, so that the conductive material, carbon, effectively imparts electron conductivity to sulfur. It has the advantage of being able to do it.
또한, 상기 황-탄소 복합체(11)에 있어서, 상기 황은 황(S8), Li2Sn(n은 n≥1의 실수임.), 유기 황 화합물 및 탄소-황 폴리머[(C2Sx)n, x는 2. 내지 50의 실수임, n은 n≥2인 실수임]로 이루어진 군에서 선택되는 1종 이상일 수 있다.In addition, in the sulfur-carbon composite 11, the sulfur is sulfur (S 8 ), Li 2 S n (n is a real number of n≥1), an organic sulfur compound and a carbon-sulfur polymer [(C 2 S x ) n , x is a real number of 2. to 50, n is a real number of n≥2] may be one or more selected from the group consisting of.
또한, 상기 탄소는 그라파이트, 그래핀, 수퍼 P, 카본 블랙, 덴카 블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼네이스 블랙, 램프 블랙, 서머 블랙, 탄소 섬유, 탄소 나노 섬유, 탄소나노튜브, 탄소 나노 와이어, 탄소 나노 링, 탄소 직물 및 플러렌(C60)로 이루어진 군에서 선택되는 1종 이상인 것일 수 있다.In addition, the carbon is graphite, graphene, super P, carbon black, denka black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, carbon nanofiber, carbon nanotube, carbon It may be one or more selected from the group consisting of nanowires, carbon nanorings, carbon fabrics, and fullerenes (C60).
또한, 상기 황-탄소 복합체(11)의 직경은 5 내지 100 ㎛, 바람직하게는 10 내지 70㎛, 보다 바람직하게는 15 내지 60 ㎛ 일 수 있다. 이때, 황-탄소 복합체(11)의 직경이란 상기 황-탄소 복합체 입자의 단면에서 최장축의 길이를 의미한다. 상기 범위 미만이면 전도성 고분자 나노섬유가 코팅할 표면적이 지나치게 크므로 상기 표면적을 모두 코팅할 수 없어 코팅의 효과가 나타나지 않을 수 있으며, 상기 범위 초과 이면 전극 형성시 불균일도가 커져 성능에 부영향을 끼칠 수 있다.In addition, the diameter of the sulfur-carbon composite 11 may be 5 to 100 μm, preferably 10 to 70 μm, and more preferably 15 to 60 μm. At this time, the diameter of the sulfur-carbon composite 11 means the length of the longest axis in the cross section of the sulfur-carbon composite particles. If it is less than the above range, the surface area to be coated by the conductive polymer nanofiber is too large to coat all of the surface area, so that the effect of coating may not be exhibited. You can.
상기 황과 탄소의 중량비는 60:40 내지 90:10, 바람직하게는 65:35 내지 85:15, 보다 바람직하게는 70:30 내지 80:20 일 수 있다. 상기 황에 대한 탄소의 중량비가 상기 범위 미만이면 전도성이 저하될 수 있고, 상기 범위 초과이면 활물질의 양이 줄어 에너지 밀도가 저하될 수 있다.The weight ratio of sulfur and carbon may be 60:40 to 90:10, preferably 65:35 to 85:15, and more preferably 70:30 to 80:20. If the weight ratio of carbon to sulfur is less than the above range, conductivity may be lowered, and if it is above the above range, the amount of active material may be reduced and energy density may be lowered.
황-탄소 복합체의 제조방법Manufacturing method of sulfur-carbon composite
본 발명은 또한, 전도성 고분자 코팅층을 포함하는 황-탄소 복합체의 제조방법에 관한 것으로, 상기 황-탄소 복합체의 제조방법은, (S1) 전도성 고분자를 포함하는 농축 분산액을 제조하는 단계; (S2) 황 분말과 탄소 소재를 혼합하여 황-탄소 복합체를 제조하는 단계; 및 (S3) 상기 농축 분산액과 황-탄소 복합체를 혼합하고 건조시켜 상기 황-탄소 복합체에 전도성 고분자 코팅층을 형성하는 단계;를 포함한다.The present invention also relates to a method for producing a sulfur-carbon composite comprising a conductive polymer coating layer, wherein the method for producing a sulfur-carbon composite comprises: (S1) preparing a concentrated dispersion containing a conductive polymer; (S2) preparing a sulfur-carbon composite by mixing a sulfur powder and a carbon material; And (S3) mixing and drying the concentrated dispersion and a sulfur-carbon composite to form a conductive polymer coating layer on the sulfur-carbon composite.
이하, 각 단계별로 본 발명에 따른 황-탄소 복합체의 제조방법을 보다 상세히 설명한다.Hereinafter, a method of manufacturing the sulfur-carbon composite according to the present invention in each step will be described in more detail.
(S1) 단계(S1) step
(S1) 단계에서는, 전도성 고분자를 포함하는 농축 분산액을 제조할 수 있다.In the step (S1), it is possible to prepare a concentrated dispersion containing a conductive polymer.
상기 전도성 고분자는 네트워크형 코팅층을 형성할 수 있는 형상을 가지는 것일 수 있다. 상기 전도성 고분자의 구체적인 종류 및 형상은 전술한 바와 같다. 바람직하게는 상기 전도성 고분자는 폴리아닐린 나노섬유일 수 있다.The conductive polymer may have a shape capable of forming a network-type coating layer. Specific types and shapes of the conductive polymer are as described above. Preferably, the conductive polymer may be polyaniline nanofibers.
상기 전도성 고분자를 물에 분산 및 여과시키는 과정을 수차례 반복하여 전도성 고분자를 포함하는 농축 분산액을 제조할 수 있다.The process of dispersing and filtering the conductive polymer in water may be repeated several times to prepare a concentrated dispersion containing the conductive polymer.
(S2) 단계(S2) step
(S2) 단계에서는, 황과 탄소를 혼합하여 황-탄소 복합체를 제조할 수 있다.In step (S2), sulfur and carbon may be mixed to prepare a sulfur-carbon composite.
이때, 황과 탄소는 각각 입자 형태로서, 황과 탄소의 구체적인 종류과 직경은 전술한 바와 같다.At this time, sulfur and carbon are each in the form of particles, and the specific types and diameters of sulfur and carbon are as described above.
구체적으로는, 유기 용매에 황과 탄소를 분산시켜, 가열하여 용융 확산법에 의해 황을 용융시키며 혼합하여 황-탄소 복합체를 형성할 수 있다.Specifically, sulfur and carbon may be dispersed in an organic solvent, heated, and melted and mixed by a melt diffusion method to form a sulfur-carbon composite.
이때, 상기 유기 용매는 디메틸설폭시드, 디에틸렌글리콜메틸에틸에테르, 에틸렌글리콜부틸에테르 및 2-부톡시에틸아세테이트로 이루어진 군에서 선택되는 1종 이상일 수 있으나, 이에 제한되는 것은 아니며, 황과 탄소를 분산시킬 수 있는 유기 용매를 광범위하게 사용할 수 있다.At this time, the organic solvent may be one or more selected from the group consisting of dimethyl sulfoxide, diethylene glycol methyl ethyl ether, ethylene glycol butyl ether, and 2-butoxyethyl acetate, but is not limited thereto. A wide range of organic solvents that can be dispersed can be used.
또한, 상기 가열시 온도는 황의 녹는점 이상일 수 있다. 즉, 상기 가열시 온도는 115.21 ℃ 이상, 바람직하게는 130 내지 200 ℃, 보다 바람직하게는 150 내지 200 ℃일 수 있다. 상기 범위 미만이면 황이 녹지 않아 황-탄소 복합체를 형성할 수 없고, 상기 범위 초과이면 황-탄소 복합체가 변성되어 리튬 이차전지의 양극재로 적용시 전지의 성능 개선 효과가 미미할 수 있다.In addition, the temperature at the time of heating may be more than the melting point of sulfur. That is, the temperature during heating may be 115.21 ° C or higher, preferably 130 to 200 ° C, and more preferably 150 to 200 ° C. If it is less than the above range, sulfur cannot be melted to form a sulfur-carbon composite. If it is more than the above range, the sulfur-carbon composite is denatured and the effect of improving the performance of the battery may be insignificant when applied as a cathode material for a lithium secondary battery.
(S3) 단계(S3) step
(S3) 단계에서는, 상기 (S1) 단계에서 얻은 전도성 고분자를 포함하는 농축 분산액, 상기 (S2) 단계에서 얻은 황-탄소 복합체 및 용매를 혼합하고 건조시켜 상기 황-탄소 복합체에 전도성 고분자 코팅층을 형성할 수 있다.In the step (S3), a concentrated dispersion containing the conductive polymer obtained in the step (S1), a sulfur-carbon composite obtained in the step (S2) and a solvent are mixed and dried to form a conductive polymer coating layer on the sulfur-carbon composite can do.
상기 용매는 상기 황-탄소 복합체와 친화성이 좋은 용매로서, 물, 에탄올, 아세톤, 디클로로메탄 및 1-메틸-2-피롤리돈으로 이루어진 군에서 선택되는 1종 이상일 수 있다.The solvent is a solvent having good affinity with the sulfur-carbon complex, and may be one or more selected from the group consisting of water, ethanol, acetone, dichloromethane and 1-methyl-2-pyrrolidone.
리튬 이차전지Lithium secondary battery
본 발명은 또한, 전술한 바와 같은 황-탄소 복합체를 포함하는 리튬 이차전지에 관한 것이다. 이때, 상기 황-탄소 복합체는 바람직하게는 양극 활물질로 포함될 수 있다. The present invention also relates to a lithium secondary battery comprising a sulfur-carbon composite as described above. At this time, the sulfur-carbon composite may be preferably included as a positive electrode active material.
본 발명에 따른 리튬 이차전지는 양극, 음극, 이들 사이에 개재된 분리막 및 전해질을 포함할 수 있다.The lithium secondary battery according to the present invention may include a positive electrode, a negative electrode, a separator interposed therebetween, and an electrolyte.
본 발명에 있어서, 상기 리튬 이차전지의 양극은 양극 집전체 및 상기 양극 집전체 상에 형성된 양극 활물질을 갖는 양극 합제층을 포함할 수 있다. In the present invention, the positive electrode of the lithium secondary battery may include a positive electrode current collector and a positive electrode mixture layer having a positive electrode active material formed on the positive electrode current collector.
상기 양극 활물질로는 리튬 함유 전이금속 산화물이 바람직하게 사용될 수 있으며, 예를 들면 LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li(NiaCobMnc)O2(0<a<1, 0<b<1, 0<c<1, a+b+c=1), LiNi1 - yCoyO2, LiCo1 - yMnyO2, LiNi1 - yMnyO2(O≤y<1), Li(NiaCobMnc)O4(0<a<2, 0<b<2, 0<c<2, a+b+c=2), LiMn2 - zNizO4, LiMn2 - zCozO4(0<z<2), LiCoPO4 및 LiFePO4로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 사용할 수 있다. 또한, 이러한 산화물(oxide) 외에 황화물(sulfide), 셀렌화물(selenide) 및 할로겐화물(halide) 등도 사용될 수 있다.Lithium-containing transition metal oxide may be preferably used as the positive electrode active material, for example, LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , Li (Ni a Co b Mn c ) O 2 (0 <a < 1, 0 <b <1, 0 <c <1, a + b + c = 1), LiNi 1 - y Co y O 2 , LiCo 1 - y Mn y O 2 , LiNi 1 - y Mn y O 2 ( O≤y <1), Li (Ni a Co b Mn c ) O 4 (0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), LiMn 2 - z Ni z O 4 , LiMn 2 - z Co z O 4 (0 <z <2), any one selected from the group consisting of LiCoPO 4 and LiFePO 4 or a mixture of two or more of them may be used. In addition, sulfides, selenides, and halides may be used in addition to these oxides.
또한, 상기 양극 집전체는 당해 전지에 화학적 변화를 유발하지 않으면서 높은 도전성을 가지는 것이라면 특별히 제한되지 않으며, 예를 들면 스테인리스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 또는 알루미늄이나 스테인리스 스틸의 표면에 카본, 니켈, 티탄, 은 등으로 표면 처리한 것 등이 사용될 수 있다. 이때, 상기 양극 집전체는 양극 활물질과의 접착력을 높일 수도 있도록, 표면에 미세한 요철이 형성된 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태를 사용할 수 있다.In addition, the positive electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. Carbon, nickel, titanium, silver or the like may be used. At this time, the positive electrode current collector may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabrics, etc. with fine irregularities formed on the surface so as to increase adhesion with the positive electrode active material.
본 발명에 있어서, 상기 리튬 이차전지의 음극은 음극 집전체 및 상기 음극 집전체 상에 형성된 음극 활물질을 갖는 음극 합제층을 포함할 수 있다. In the present invention, the negative electrode of the lithium secondary battery may include a negative electrode current collector and a negative electrode mixture layer having a negative electrode active material formed on the negative electrode current collector.
상기 음극 활물질로는 통상적으로 리튬이온이 흡장 및 방출될 수 있는 탄소재, 리튬금속, 규소 또는 주석 등을 사용할 수 있다. 바람직하게는 탄소재를 사용할 수 있는데, 탄소재로는 저결정 탄소 및 고결정성 탄소 등이 모두 사용될 수 있다. 저결정성 탄소로는 연화탄소(soft carbon) 및 경화탄소(hard carbon)가 대표적이며, 고결정성 탄소로는 천연 흑연, 키시흑연(Kish graphite), 열분해 탄소(pyrolytic carbon), 액정 피치계 탄소섬유(mesophase pitch based carbon fiber), 탄소 미소구체(meso-carbon microbeads), 액정피치(Mesophase pitches) 및 석유와 석탄계 코크스(petroleum or coal tar pitch derived cokes) 등의 고온 소성탄소가 대표적이다. 이때 음극은 결착제를 포함할 수 있으며, 결착제로는 비닐리덴플루오라이드-헥사플루오로프로필렌 코폴리머(PVDF-co-HFP), 폴리비닐리덴플루오라이드(polyvinylidenefluoride), 폴리아크릴로니트릴(polyacrylonitrile), 폴리메틸메타크릴레이트(polymethylmethacrylate) 등, 다양한 종류의 바인더 고분자가 사용될 수 있다.As the negative electrode active material, a carbon material, lithium metal, silicon, or tin, which can normally occlude and release lithium ions, can be used. Preferably, a carbon material can be used, and both low-crystalline carbon and high-crystalline carbon may be used as the carbon material. Soft carbon and hard carbon are typical examples of low crystalline carbon, and natural graphite, Kish graphite, pyrolytic carbon, and liquid crystal pitch-based carbon fibers are examples of high crystalline carbon. High-temperature calcined carbon such as (mesophase pitch based carbon fiber), meso-carbon microbeads, Mesophase pitches, and petroleum or coal tar pitch derived cokes are typical examples. At this time, the negative electrode may include a binder, and as a binder, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (polyvinylidenefluoride), polyacrylonitrile (polyacrylonitrile), Various types of binder polymers, such as polymethylmethacrylate, can be used.
또한, 상기 음극 집전체는 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되지 않으며, 예를 들면 구리, 스테인리스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 구리나 스테인리스 스틸의 표면에 카본, 니켈, 티탄, 은 등으로 표면 처리한 것, 알루미늄-카드뮴 합금 등이 사용될 수 있다. 또한, 상기 음극 집전체는 양극 집전체와 마찬가지로, 표면에 미세한 요철이 형성된 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태가 사용될 수 있다.In addition, the negative electrode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel. Carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloy, or the like may be used. In addition, the cathode current collector, like the anode current collector, various forms such as a film, sheet, foil, net, porous body, foam, and non-woven fabric having fine irregularities on the surface may be used.
이때, 상기 양극 합제층 또는 음극 합제층은 바인더 수지, 도전재, 충진제 및 기타 첨가제 등을 추가로 포함할 수 있다.At this time, the positive electrode mixture layer or the negative electrode mixture layer may further include a binder resin, a conductive material, a filler, and other additives.
상기 바인더 수지는 전극 활물질과 도전재의 결합과 집전체에 대한 결합을 위해 사용한다. 이러한 바인더 수지의 예로는, 폴리비닐리덴플로라이드(PVDF), 폴리비닐알코올, 카르복시메틸셀룰로우즈(CMC), 전분, 하이드록시프로필셀룰로우즈, 재생 셀룰로우즈, 폴리비닐피롤리돈, 테트라플루오로에틸렌, 폴리에틸렌, 폴리프로필렌, 에틸렌-프로필렌-디엔 폴리머(EPDM), 술폰화-EPDM, 스티렌-부타디엔 고무, 불소 고무, 이들의 다양한 공중합체 등을 들 수 있다.The binder resin is used for bonding the electrode active material and the conductive material and bonding to the current collector. Examples of such a binder resin include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetra And fluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, and various copolymers thereof.
상기 도전재는 전극 활물질의 도전성을 더욱 향상시키기 위해 사용한다.　이러한 도전재는 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 천연 흑연이나 인조 흑연 등의 흑연; 카본블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼니스 블랙, 램프 블랙, 서머 블랙 등의 카본블랙; 탄소 섬유나 금속 섬유 등의 도전성 섬유; 불화 카본, 알루미늄, 니켈 분말 등의 금속 분말; 산화아연, 티탄산 칼륨 등의 도전성 휘스커; 산화티탄 등의 도전성 금속 산화물; 폴리페닐렌 유도체 등이 사용될 수 있다.The conductive material is used to further improve the conductivity of the electrode active material. The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer 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; Polyphenylene derivatives and the like can be used.
상기 충진제는 전극의 팽창을 억제하는 성분으로서 선택적으로 사용되며, 당해 전지에 화학적 변화를 유발하지 않으면서 섬유상 재료라면 특별히 제한되는 것은 아니며, 예를 들어, 폴리에틸렌, 폴리프로필렌 등의 올리핀계 중합체; 유리섬유, 탄소섬유 등의 섬유상 물질이 사용된다.The filler is selectively used as a component that suppresses the expansion of the electrode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. For example, olefinic polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.
본 발명에 있어서, 상기 분리막은 다공성 기재로 이루어질 수 있으며, 상기 다공성 기재는, 통상적으로 전기화학소자에 사용되는 다공성 기재라면 모두 사용이 가능하고, 예를 들면 폴리올레핀계 다공성 막(membrane) 또는 부직포를 사용할 수 있으나, 이에 특별히 한정되는 것은 아니다.In the present invention, the separation membrane may be made of a porous substrate, and the porous substrate may be any porous substrate commonly used in electrochemical devices, for example, a polyolefin-based porous membrane (membrane) or non-woven fabric. It can be used, but is not particularly limited thereto.
상기 폴리올레핀계 다공성 막의 예로는, 고밀도 폴리에틸렌, 선형 저밀도 폴리에틸렌, 저밀도 폴리에틸렌, 초고분자량 폴리에틸렌과 같은 폴리에틸렌, 폴리프로필렌, 폴리부틸렌, 폴리펜텐 등의 폴리올레핀계 고분자를 각각 단독으로 또는 이들을 혼합한 고분자로 형성한 막(membrane)을 들 수 있다.Examples of the polyolefin-based porous membrane include polyolefin-based polymers such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene, polypropylene, polybutylene, and polypentene, respectively, alone or as a mixture of these. One membrane is mentioned.
상기 부직포로는 폴리올레핀계 부직포 외에 예를 들어, 폴리에틸렌 테레프탈레이트 (polyethyleneterephthalate), 폴리부틸렌 테레프탈레이트 (polybutyleneterephthalate), 폴리에스테르 (polyester), 폴리아세탈 (polyacetal), 폴리아미드 (polyamide), 폴리카보네이트 (polycarbonate), 폴리이미드 (polyimide), 폴리에테르에테르케톤 (polyetheretherketone), 폴리에테르설폰 (polyethersulfone), 폴리페닐렌 옥사이드 (polyphenyleneoxide), 폴리페닐렌 설파이드 (polyphenylenesulfide) 및 폴리에틸렌 나프탈렌 (polyethylenenaphthalene) 등을 각각 단독으로 또는 이들을 혼합한 고분자로 형성한 부직포를 들 수 있다. 부직포의 구조는 장섬유로 구성된 스폰본드 부직포 또는 멜트 블로운 부직포일 수 있다.The nonwoven fabric includes, in addition to the polyolefin nonwoven fabric, for example, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate ), Polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, and polyethylene naphthalene, respectively, or And nonwoven fabrics formed of polymers in which these are mixed. The structure of the nonwoven fabric may be a spunbond nonwoven fabric composed of long fibers or a melt blown nonwoven fabric.
상기 다공성 기재의 두께는 특별히 제한되지 않으나, 1 ㎛ 내지 100 ㎛, 또는 5 ㎛ 내지 50 ㎛이다.The thickness of the porous substrate is not particularly limited, but is 1 μm to 100 μm, or 5 μm to 50 μm.
다공성 기재에 존재하는 기공의 크기 및 기공도 역시 특별히 제한되지 않으나 각각 0.001㎛ 내지 50㎛ 및 10% 내지 95%일 수 있다.The size and pores of the pores present in the porous substrate are also not particularly limited, but may be 0.001 μm to 50 μm and 10% to 95%, respectively.
본 발명에 있어서, 상기 전해액은 비수 전해액일 수 있으며, 상기 비수 전해액에 포함되는 전해질 염은 리튬염이다. 상기 리튬염은 리튬 이차전지용 전해액에 통상적으로 사용되는 것들 것 제한 없이 사용될 수 있다. 예를 들어 상기 리튬염은 LiFSI, LiPF6, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl10, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiPF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2)2NLi, 클로로 보란 리튬 및 4-페닐 붕산 리튬으로 이루어진 군에서 선택되는 1종 이상일 수 있다.In the present invention, the electrolyte solution may be a non-aqueous electrolyte solution, and the electrolyte salt contained in the non-aqueous electrolyte solution is a lithium salt. The lithium salt may be used without limitation to those commonly used in electrolytes for lithium secondary batteries. For example, the lithium salt is LiFSI, LiPF 6 , LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiPF 6 , LiAlCl 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, chloroborane lithium, and 4-phenyl lithium borate.
전술한 비수 전해액에 포함되는 유기 용매로는 리튬 이차전지용 전해액에 통상적으로 사용되는 것들을 제한 없이 사용할 수 있으며, 예를 들면 에테르, 에스테르, 아미드, 선형 카보네이트, 환형 카보네이트 등을 각각 단독으로 또는 2종 이상 혼합하여 사용할 수 있다. 그 중에서 대표적으로는 환형 카보네이트, 선형 카보네이트, 또는 이들의 슬러리인 카보네이트 화합물을 포함할 수 있다.As the organic solvent included in the above-mentioned non-aqueous electrolyte, those commonly used in electrolytes for lithium secondary batteries can be used without limitation, for example, ether, ester, amide, linear carbonate, cyclic carbonate, etc. alone or in combination of two or more, respectively. It can be used by mixing. Among them, a cyclic carbonate, a linear carbonate, or a carbonate compound that is a slurry thereof may be included.
상기 환형 카보네이트 화합물의 구체적인 예로는 에틸렌 카보네이트(ethylene carbonate, EC), 프로필렌 카보네이트(propylene carbonate, PC), 1,2-부틸렌 카보네이트, 2,3-부틸렌 카보네이트, 1,2-펜틸렌 카보네이트, 2,3-펜틸렌 카보네이트, 비닐렌 카보네이트, 비닐에틸렌 카보네이트 및 이들의 할로겐화물로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 슬러리가 있다. 이들의 할로겐화물로는 예를 들면, 플루오로에틸렌 카보네이트(fluoroethylene carbonate, FEC) 등이 있으며, 이에 한정되는 것은 아니다.Specific examples of the cyclic carbonate compound are ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-Pentylene carbonate, vinylene carbonate, vinyl ethylene carbonate and any one selected from the group consisting of halides, or a slurry of two or more of them. Examples of these halides include, but are not limited to, fluoroethylene carbonate (FEC).
또한, 상기 선형 카보네이트 화합물의 구체적인 예로는 디메틸 카보네이트(DMC), 디에틸 카보네이트(DEC), 디프로필 카보네이트, 에틸메틸 카보네이트(EMC), 메틸프로필 카보네이트 및 에틸프로필 카보네이트로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 슬러리 등이 대표적으로 사용될 수 있으나, 이에 한정되는 것은 아니다. 특히, 상기 카보네이트계 유기 용매 중 환형 카보네이트인 에틸렌 카보네이트 및 프로필렌 카보네이트는 고점도의 유기 용매로서 유전율이 높아 전해질 내의 리튬염을 보다 더 잘 해리시킬 수 있으며, 이러한 환형 카보네이트에 디메틸 카보네이트 및 디에틸 카보네이트와 같은 저점도, 저유전율 선형 카보네이트를 적당한 비율로 혼합하여 사용하면 보다 높은 전기 전도율을 갖는 전해액을 만들 수 있다.In addition, specific examples of the linear carbonate compound may be any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate, or Of these, two or more types of slurries may be typically used, but are not limited thereto. In particular, among the carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents and have higher dielectric constants, so that lithium salts in the electrolyte can be better dissociated, such as dimethyl carbonate and diethyl carbonate. When a low-viscosity, low-permittivity linear carbonate is mixed and used in an appropriate ratio, an electrolyte having a higher electrical conductivity can be produced.
또한, 상기 유기 용매 중 에테르로는 디메틸 에테르, 디에틸 에테르, 디프로필 에테르, 메틸에틸 에테르, 메틸프로필 에테르 및 에틸프로필 에테르로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 슬러리를 사용할 수 있으나, 이에 한정되는 것은 아니다.In addition, as the ether in the organic solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether and ethylpropyl ether, or a slurry of two or more of them may be used. , But is not limited thereto.
또한, 상기 유기 용매 중 에스테르로는 메틸 아세테이트, 에틸 아세테이트, 프로필 아세테이트, 메틸 프로피오네이트, 에틸 프로피오네이트, 프로필 프로피오네이트, γ-부티로락톤, γ-발레로락톤, γ-카프로락톤, σ-발레로락톤 및 ε-카프로락톤으로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 슬러리를 사용할 수 있으나, 이에 한정되는 것은 아니다.In addition, esters of the organic solvent include methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, Any one selected from the group consisting of σ-valerolactone and ε-caprolactone or a slurry of two or more of them may be used, but is not limited thereto.
상기 비수 전해액의 주입은 최종 제품의 제조 공정 및 요구 물성에 따라, 전기화학소자의 제조 공정 중 적절한 단계에서 행해질 수 있다. 즉, 전기화학소자 조립 전 또는 전기화학소자 조립 최종 단계 등에서 적용될 수 있다.The injection of the non-aqueous electrolyte may be performed at an appropriate step in the manufacturing process of the electrochemical device, depending on the manufacturing process of the final product and the required physical properties. That is, it can be applied before the electrochemical device assembly or at the final stage of the electrochemical device assembly.
본 발명에 따른 리튬 이차전지는, 일반적인 공정인 권취(winding) 이외에도 세퍼레이터와 전극의 적층(lamination, stack) 및 접음(folding) 공정이 가능하다.In the lithium secondary battery according to the present invention, a lamination, stacking, and folding process of a separator and an electrode may be performed in addition to winding, which is a general process.
그리고, 상기 전지케이스의 형상은 특별히 제한되지 않으며, 원통형, 적층형, 각형, 파우치(pouch)형 또는 코인(coin)형 등 다양한 형상으로 할 수 있다. 이들 전지의 구조와 제조 방법은 이 분야에 널리 알려져 있으므로 상세한 설명은 생략한다.In addition, the shape of the battery case is not particularly limited, and may be various shapes such as a cylindrical shape, a stacked shape, a square shape, a pouch shape, or a coin shape. The structure and manufacturing method of these batteries are well known in the art, so detailed descriptions thereof are omitted.
또한, 상기 리튬 이차전지는 사용하는 양극/음극 재질에 따라 리튬-황 이차전지, 리튬-공기 전지, 리튬-산화물 전지, 리튬 전고체 전지 등 다양한 전지로 분류가 가능하다.In addition, the lithium secondary battery may be classified into various batteries such as a lithium-sulfur secondary battery, a lithium-air battery, a lithium-oxide battery, and a lithium solid-state battery according to the anode / cathode material used.
본 발명은 또한, 상기 리튬 이차전지를 단위전지로 포함하는 전지모듈을 제공한다.The present invention also provides a battery module including the lithium secondary battery as a unit cell.
상기 전지모듈은 고온 안정성, 긴 사이클 특성 및 높은 용량 특성 등이 요구되는 중대형 디바이스의 전원으로 사용될 수 있다.The battery module can be used as a power source for medium to large-sized devices that require high temperature stability, long cycle characteristics, and high capacity characteristics.
상기 중대형 디바이스의 예로는 전지적 모터에 의해 동력을 받아 움직이는 파워 툴(power tool); 전기자동차(electric vehicle, EV), 하이브리드 전기자동차(hybrid electric vehicle, HEV), 플러그-인 하이브리드 전기자동차(plug-in hybrid electric vehicle, PHEV) 등을 포함하는 전기차; 전기 자전거(E-bike), 전기 스쿠터(E-scooter)를 포함하는 전기 이륜차; 전기 골프 카트(electric golf cart); 전력저장용 시스템 등을 들 수 있으나, 이에 한정되는 것은 아니다.Examples of the medium-to-large-sized device include a power tool that is powered by an omniscient motor and moves; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like; Electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); Electric golf carts; A power storage system, and the like, but is not limited thereto.
리튬-황 이차전지Lithium-sulfur secondary battery
본 발명은 따른 황-탄소 복합체는 리튬 이차전지 중에서도, 리튬-황 이차전지의 양극에 적용할 수 있다. The sulfur-carbon composite according to the present invention can be applied to a positive electrode of a lithium-sulfur secondary battery, among lithium secondary batteries.
이때, 상기 리튬-황 이차전지는 양극 활물질로서 상기 황-탄소 복합체를 포함하는 전지일 수 있다. In this case, the lithium-sulfur secondary battery may be a battery including the sulfur-carbon composite as a positive electrode active material.
상기 황-탄소 복합체는 기공 내부까지 리튬 이온의 이동 경로를 확보함으로써 높은 이온 전도성을 나타낼 수 있고, 황 담지체의 역할을 하여 양극 활물질인 황과의 반응성을 높여 리튬-황 이차전지의 용량 및 수명 특성을 동시에 향상시킬 수 있다.The sulfur-carbon composite can exhibit high ionic conductivity by securing the path of lithium ions to the inside of the pores, and acts as a sulfur carrier to increase the reactivity with the positive electrode active material, sulfur, and the capacity and life of the lithium-sulfur secondary battery The characteristics can be improved at the same time.
이하 본 발명의 이해를 돕기 위하여 바람직한 실시예를 제시하나, 하기 실시예는 본 발명을 예시하는 것일 뿐 본 발명의 범주 및 기술사상 범위 내에서 다양한 변경 및 수정이 가능함은 당업자에게 있어서 명백한 것이며, 이러한 변경 및 수정이 첨부된 특허청구범위에 속하는 것도 당연한 것이다.Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely illustrative of the present invention, and it is apparent to those skilled in the art that various changes and modifications can be made within the scope and technical scope of the present invention. It is natural that changes and modifications fall within the scope of the appended claims.
제조예Manufacturing example 1:  One: 폴리아닐린Polyaniline 나노섬유의 합성 Synthesis of nanofibers
전도성 고분자인 폴리아닐린 나노섬유의 합성은 Jiaxing Huang et al. (Nanofiber Formation in the Chemical Polymerization of Aniline: A Mechanistic Study Angew. Chem. Int. Ed. 2004, 43, 5817-5821) 에 따라 실시하였다.Synthesis of conductive polymer polyaniline nanofibers was performed by Jiaxing Huang et al. (Nanofiber Formation in the Chemical Polymerization of Aniline: A Mechanistic Study Angew. Chem. Int. Ed. 2004, 43, 5817-5821).
아닐린(aniline)을 1M HCl에 용해시켜 0.32 M의 아닐린 용액 100 ml을 제조하였다.Aniline was dissolved in 1M HCl to prepare 100 ml of a 0.32 M aniline solution.
과황산암모늄(ammonium persulfate)을 1M HCl에 용해시켜 0.08M 과황산암모늄 용액 100 ml을 제조하였다.Ammonium persulfate was dissolved in 1M HCl to prepare 100 ml of a 0.08M ammonium persulfate solution.
상기 아닐린 용액과 과황산암모늄 용액을 혼합하여 혼합 용액을 얻었다.The aniline solution and ammonium persulfate solution were mixed to obtain a mixed solution.
상기 혼합 용액 형성 시 상온에서 빠르게 혼합하면서 초기 반응을 실시한 후, 상기 혼합 용액의 상태에서 10시간 동안 추가 반응을 실시하여, 폴리아닐린 나노섬유 분산액을 제조하였다.When the mixed solution was formed, the initial reaction was performed while rapidly mixing at room temperature, followed by additional reaction for 10 hours in the state of the mixed solution to prepare a polyaniline nanofiber dispersion.
실시예Example 1 One
(( 1)황1) sulfur -탄소 복합체 제조-Carbon composite production
(1-1)전도성 고분자를 포함하는 농축 분산액 제조(1-1) Preparation of concentrated dispersion containing a conductive polymer
제조예 1에서 얻은 폴리아닐린 나노섬유 분산액을 여과시켜 잔여 반응물을 제외한 폴리아닐린 나노섬유를 걸러내고, 수차례 물에 재분산 및 재여과를 거쳐 pH를 6 이상으로 중화시켜, 농도가 5%인 폴리아닐린 나노섬유 농축 분산액을 얻었다.The polyaniline nanofiber dispersion obtained in Preparation Example 1 was filtered to filter out polyaniline nanofibers excluding the remaining reactants, and after being redispersed and re-filtered in water several times to neutralize the pH to 6 or higher, polyaniline nanofibers having a concentration of 5% A concentrated dispersion was obtained.
(1-2)황-탄소 복합체 제조(1-2) Preparation of sulfur-carbon composite
탄소나노튜브와 황을 25 : 75 의 중량비로 혼합하고, 155℃에서 용융 확산법을 통해 탄소에 황을 담지하여 황-탄소 복합체를 제조하였다.A sulfur-carbon composite was prepared by mixing carbon nanotubes and sulfur in a weight ratio of 25:75 and supporting sulfur on carbon through a melt diffusion method at 155 ° C.
(1-3)네트워크형 전도성 고분자 코팅층 형성(1-3) Formation of network-type conductive polymer coating layer
상기 (1)에서 얻은 폴리아닐린 나노섬유 농축 분산액, 상기 (2)에서 얻은 황-탄소 복합체 및 에탄올을 1 : 1 : 1의 중량비로 혼합하였다. The polyaniline nanofiber concentrated dispersion obtained in (1), the sulfur-carbon composite obtained in (2) and ethanol were mixed in a weight ratio of 1: 1.
혼합 후 얻은 혼합 용액을 건조시켜 용매를 제거함으로써, 폴리아닐린 나노섬유 코팅층이 형성된 황-탄소 복합체를 제조하였다. 이때, 상기 폴리아닐린 나노섬유 코팅층이 형성된 황-탄소 복합체 내에 포함된 폴리아닐린은 5 중량%이다.The mixed solution obtained after mixing was dried to remove the solvent, thereby preparing a sulfur-carbon composite having a polyaniline nanofiber coating layer. At this time, the polyaniline contained in the sulfur-carbon composite on which the polyaniline nanofiber coating layer is formed is 5% by weight.
(( 2)양극2) anode 제조 Produce
Al 집전체의 일면에 상기 황-탄소 복합체를 포함하는 양극 합제층이 형성하여 양극을 제조하였다. 이때, 상기 양극 합제층은 상기 황-탄소 복합체, 바인더로서 폴리아크릴릭산(PAA) 및 카본블랙을 88 : 7 : 5 의 중량비로 혼합한 후 물에 분산시킨 슬러리를 상기 Al 집전체의 일면에 코팅 및 건조하여 건조 시킨 후 제조하였다. An anode mixture layer including the sulfur-carbon composite was formed on one surface of the Al current collector to prepare an anode. At this time, the positive electrode mixture layer is a mixture of polyacrylic acid (PAA) and carbon black as a weight ratio of 88: 7: 5 as the sulfur-carbon composite and a binder, and then a slurry dispersed in water is coated on one surface of the Al current collector. And dried and dried.
(3) 리튬-황 이차전지 제조(3) Lithium-sulfur secondary battery manufacturing
음극으로서 100 ㎛ 두께의 리튬 호일, 상기 (2)에서 제조된 양극, 전해액은 용매로서 2-METHF/DME을 사용하고, LiTFSI와 LiNO3를 포함하는(2-METHF: 2-메틸테트라하이드로퓨란, DME: 디메톡시에탄) 전해액 및 폴리올레핀 분리막을 사용하여 코인셀 형태의 리튬-황 이차전지를 제조하였다.A lithium foil having a thickness of 100 μm as a negative electrode, the positive electrode prepared in (2), 2-METHF / DME as an electrolyte, and containing LiTFSI and LiNO 3 (2-METHF: 2-methyltetrahydrofuran, DME: Dimethoxyethane) A lithium-sulfur secondary battery in the form of a coin cell was prepared using an electrolyte and a polyolefin separator.
비교예Comparative example 1 One
실시예 1과 동일하게 실시하되, 폴리아닐린 나노섬유 코팅층이 형성되지 않은 황-탄소 복합체를 제조하였다.A sulfur-carbon composite was prepared in the same manner as in Example 1, but the polyaniline nanofiber coating layer was not formed.
비교예Comparative example 2 2
비교예 1과 같이 폴리아닐린 나노섬유 코팅층이 형성되지 않은 상태의 황-탄소 복합체를 제조한 후, 코인셀 제작시 전해액에 아닐린을 첨가하고, 충전 전압을 가하여, 상기 황-탄소 복합체의 표면에 막 형태의 폴리아닐린 코팅층을 형성하였다. 이때, 상기 아닐린의 첨가량은, 폴리아닐린 코팅층이 형성된 황-탄소 복합체 전체 중량을 기준으로 폴리아닐린의 함량이 5 중량%가 되도록 하여 첨가하였다.As in Comparative Example 1, after preparing a sulfur-carbon composite in a state where a polyaniline nanofiber coating layer is not formed, aniline is added to the electrolyte during coin cell production, and a charging voltage is applied to form a film on the surface of the sulfur-carbon composite A polyaniline coating layer was formed. At this time, the amount of the aniline was added so that the polyaniline content was 5% by weight based on the total weight of the sulfur-carbon composite on which the polyaniline coating layer was formed.
도 2는 비교예 2에 따라 아닐린을 첨가한 전해액 및 아닐린을 미첨가한 전해액에 충전 전압을 인가할 경우의 전위와 전류의 상관관계를 나타낸 그래프이다.FIG. 2 is a graph showing a correlation between electric potential and current when a charging voltage is applied to an electrolyte solution to which aniline is added and an electrolyte solution to which aniline is not added according to Comparative Example 2.
도 2를 참조하면, 전해액에 아닐린을 첨가하여 충전 전압을 인가할 경우, 황-탄소 복합체의 표면에 막 형태의 폴리아닐린 코팅층이 형성된 것을 알 수 있다. 이는 충전 전압을 인가할 경우, 전극에서 전기화학적으로 아닐린의 산화가 일어나 중합되어 폴리아닐린이 생성되는 원리에 의한 것이다. 즉, 전압 3.5 V에서 관찰되는 전류 증가로부터 아닐린으로부터 폴리아닐린의 전기화학적 중합을 확인할 수 있으며, 활물질 표면이 폴리아닐린 코팅층이 형성되는 것이다 (J. Mater. Chem. A, 2014, 2, 18613-18623 | 18613).Referring to FIG. 2, when a charging voltage is applied by adding aniline to an electrolyte, it can be seen that a polyaniline coating layer in the form of a film is formed on the surface of the sulfur-carbon composite. This is based on the principle that, when a charging voltage is applied, the aniline is electrochemically oxidized and polymerized at the electrode to generate polyaniline. That is, the electrochemical polymerization of polyaniline from aniline can be confirmed from the current increase observed at a voltage of 3.5 V, and the active material surface is formed with a polyaniline coating layer (J. Mater. Chem. A, 2014, 2, 18613-18623 | 18613 ).
실험예Experimental example 1:  One: SEMSEM (Scanning Electron Microscopy) 분석(Scanning Electron Microscopy) analysis
도 3a 및 3b는 각각 제조예 1에서 합성된 폴리아닐린 나노섬유 및 실시예 1에서 제조된 황-탄소 복합체의 표면에 형성된 폴리아닐린 나노섬유 코팅층에 대한 SEM 사진이다.3A and 3B are SEM photographs of the polyaniline nanofiber coating layer formed on the surfaces of the polyaniline nanofibers synthesized in Preparation Example 1 and the sulfur-carbon composite prepared in Example 1, respectively.
도 3a 및 3b를 참조하면, 폴리아닐린 나노섬유를 이용하여 황-탄소 복합체의 표면에 코팅층을 형성하여 네트워크 형상의 코팅층이 형성되는 것을 확인하였다.3A and 3B, it was confirmed that a coating layer having a network shape was formed by forming a coating layer on the surface of the sulfur-carbon composite using polyaniline nanofibers.
실험예Experimental example 2: 다공성 탄소 구조체에 의한 리튬-황 이차전지의 성능 개선 효과 분석 2: Analysis of performance improvement effect of lithium-sulfur secondary battery by porous carbon structure
실시예 1과 비교예 1에서 각각 제조된 황-탄소 복합체를 양극에 적용한 리튬-황 이차전지의 성능에 대한 실험을 실시하였다. 제조된 코인셀로 충방전 테스트를 진행하였으며, 충/방전 전류밀도는 0.1C/0.1C 3회, 0.2C/0.2C 3회, 이후 0.3C/0.5C로 평가하였다.Experiments were conducted on the performance of the lithium-sulfur secondary battery in which the sulfur-carbon composites prepared in Example 1 and Comparative Example 1 were respectively applied to the positive electrode. Charge / discharge tests were conducted with the manufactured coin cells, and the charge / discharge current density was evaluated as 0.1C / 0.1C 3 times, 0.2C / 0.2C 3 times, and then 0.3C / 0.5C.
도 4는 실시예 1, 비교예 1 및 2에서 각각 제조된 리튬-황 이차전지의 코인셀 평가 결과로서 첫 방전곡선을 나타낸 그래프이고, 도 5는 실시예 1, 비교예 1 및 2에서 각각 제조된 리튬-황 이차전지의 사이클-방전용량 곡선을 도시한 그래프이다.4 is a graph showing the first discharge curve as a result of coin cell evaluation of the lithium-sulfur secondary batteries prepared in Example 1, Comparative Examples 1 and 2, respectively, and FIG. 5 is prepared in Example 1, Comparative Examples 1 and 2, respectively. Showing a cycle-discharge curve of a lithium-sulfur secondary battery.
도 4 및 도 5를 참조하면, 비교예 1에 비해 실시예 1의 리튬-황 이차전지에서 초기 방전용량이 더 높고, 또한, 초기방전 말단구간에서 과전압이 개선되며 수명특성도 개선되는 것을 확인하였다.4 and 5, it was confirmed that the initial discharge capacity in the lithium-sulfur secondary battery of Example 1 is higher than that of Comparative Example 1, and the overvoltage is improved in the initial discharge end section and the life characteristics are also improved. .
또한, 비교예 2는 비교예 1에 비하여 과전압이 일부 개선되나, 막 형태의 폴리아닐린 코팅층이 형성되어, 방전 말단에서 전압이 감소하므로 충분한 용량을 나타내지 못하고, 실시예 1에 비해 성능이 좋지 못한 것을 확인하였다.In addition, in Comparative Example 2, although the overvoltage was partially improved compared to Comparative Example 1, a polyaniline coating layer in the form of a film was formed, so that the voltage at the discharge end was reduced, so it did not exhibit sufficient capacity, and it was confirmed that the performance was poor compared to Example 1 Did.
이상에서 본 발명은 비록 한정된 실시예와 도면에 의해 설명되었으나, 본 발명은 이것에 의해 한정되지 않으며, 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자에 의해 본 발명의 기술사상과 아래에 기재될 특허청구범위의 균등범위 내에서 다양한 수정 및 변형이 가능함은 물론이다.Although the present invention has been described above by way of limited examples and drawings, the present invention is not limited by this, and is described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the equivalent claims.
[부호의 설명][Description of codes]
10: 전도성 고분자 코팅층을 포함하는 황-탄소 복합체10: sulfur-carbon composite comprising a conductive polymer coating layer
11: 황-탄소 복합체11: sulfur-carbon complex
12: 전도성 고분자 코팅층12: conductive polymer coating layer

Claims (11)

  1. 네트워크형 전도성 고분자 코팅층을 포함하는 황-탄소 복합체.Sulfur-carbon composite comprising a network-type conductive polymer coating layer.
  2. 제1항에 있어서,According to claim 1,
    상기 전도성 고분자는 폴리아닐린(polyaniline), 폴리피롤(polypyrrole), 폴리티오펜(polythiophene), 폴리(3,4-에틸렌디옥시티오펜)(poly(3,4-ethylenedioxythiophene)), 폴리아세틸렌(polyacetylene), 폴리디아세틸렌(polydiacetylene), 폴리티오펜비닐렌(poly(thiophenevinylene)), 폴리플러렌(polyfluorene) 및 이들의 유도체로 이루어진 군에서 선택되는 1종 이상인, 황-탄소 복합체.The conductive polymer is polyaniline, polypyrrole, polythiophene, poly (3,4-ethylenedioxythiophene), polyacetylene, poly Sulfur-carbon complex, at least one member selected from the group consisting of polydiacetylene, poly (thiophenevinylene), polyfluorene and derivatives thereof.
  3. 제1항에 있어서,According to claim 1,
    상기 전도성 고분자의 형상은 나노섬유, 나노와이어, 나노로드 및 나노튜브로 이루어진 군에서 선택되는 1종 이상의 나노 구조체인, 황-탄소 복합체.The shape of the conductive polymer is one or more nanostructures selected from the group consisting of nanofibers, nanowires, nanorods, and nanotubes, a sulfur-carbon composite.
  4. 제1항에 있어서,According to claim 1,
    상기 황-탄소 복합체는The sulfur-carbon complex
    내부에 적어도 하나의 탄소 입자가 포함된 황 입자; 및Sulfur particles containing at least one carbon particle therein; And
    상기 황 입자 표면의 일부 또는 전부에 위치하는 탄소 입자;를 포함하는 것인, 황-탄소 복합체.The carbon particles located on part or all of the surface of the sulfur particles; containing, sulfur-carbon composite.
  5. 제1항에 있어서,According to claim 1,
    상기 황과 탄소의 중량비는 6:4 내지 9:1인, 황-탄소 복합체.The sulfur-carbon weight ratio is 6: 4 to 9: 1, sulfur-carbon composite.
  6. 제1항에 있어서,According to claim 1,
    상기 전도성 고분자의 함량은 상기 전도성 고분자 코팅층을 포함하는 황-탄소 복합체 전체 중량을 기준으로 0.1 내지 10 중량%인, 황-탄소 복합체.The content of the conductive polymer is 0.1 to 10% by weight based on the total weight of the sulfur-carbon composite containing the conductive polymer coating layer, sulfur-carbon composite.
  7. 제1항에 있어서,According to claim 1,
    상기 황은 황(S8), Li2Sn(n은 n≥1의 실수임.), 유기 황 화합물 및 탄소-황 폴리머[(C2Sx)n, x는 2.5 내지 50의 실수임, n은 n≥2인 실수임]로 이루어진 군에서 선택되는 1종 이상인, 황-탄소 복합체.The sulfur is sulfur (S 8 ), Li 2 S n (n is a real number of n ≧ 1.), Organic sulfur compound and carbon-sulfur polymer [(C 2 S x ) n , x is a real number of 2.5 to 50, n is a real number of n≥2], a sulfur-carbon complex of one or more selected from the group consisting of.
  8. 제1항에 있어서,According to claim 1,
    상기 탄소는 그라파이트(graphite), 그래핀(graphene), 수퍼 P(Super P), 카본 블랙, 덴카 블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼네이스 블랙, 램프 블랙, 서머 블랙, 탄소 섬유, 탄소 나노 섬유, 탄소나노튜브, 탄소 나노 와이어, 탄소 나노 링, 탄소 직물 및 플러렌(C60)로 이루어진 군에서 선택되는 1종 이상인, 황-탄소 복합체. The carbon is graphite (graphite), graphene (graphene), super P (Super P), carbon black, denka black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, carbon Sulfur-carbon composite, at least one member selected from the group consisting of nanofibers, carbon nanotubes, carbon nanowires, carbon nanorings, carbon fabrics, and fullerenes (C60).
  9. 제1항 내지 제8항 중 어느 한 항의 황-탄소 복합체를 포함하는 양극.A positive electrode comprising the sulfur-carbon complex of any one of claims 1 to 8.
  10. 제1항 내지 제8항 중 어느 한 항의 황-탄소 복합체를 포함하는 리튬 이차전지.A lithium secondary battery comprising the sulfur-carbon composite of any one of claims 1 to 8.
  11. 제10항에 있어서,The method of claim 10,
    상기 리튬 이차전지는 리튬-황 이차전지인, 리튬 이차전지.The lithium secondary battery is a lithium-sulfur secondary battery, a lithium secondary battery.
PCT/KR2019/011707 2018-09-20 2019-09-10 Sulfur-carbon composite and lithium secondary battery comprising same WO2020060097A1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US17/043,897 US12027704B2 (en) 2018-09-20 2019-09-10 Sulfur-carbon composite and lithium secondary battery comprising same
ES19863939T ES2975985T3 (en) 2018-09-20 2019-09-10 Sulfur-carbon composite material and lithium secondary battery comprising the same
CN201980031792.XA CN112106236A (en) 2018-09-20 2019-09-10 Sulfur-carbon composite and lithium secondary battery comprising same
EP19863939.5A EP3764440B1 (en) 2018-09-20 2019-09-10 Sulfur-carbon composite and lithium secondary battery comprising same
PL19863939.5T PL3764440T3 (en) 2018-09-20 2019-09-10 Sulfur-carbon composite and lithium secondary battery comprising same
JP2021503690A JP7084544B2 (en) 2018-09-20 2019-09-10 Sulfur-carbon composite and lithium secondary battery containing it
US18/731,673 US20240332528A1 (en) 2018-09-20 2024-06-03 Sulfur-carbon composite and lithium secondary battery comprising same

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR10-2018-0112636 2018-09-20
KR20180112636 2018-09-20
KR1020190111292A KR20200033737A (en) 2018-09-20 2019-09-09 Sulfur-carbon composite and lithium secondary battery including the same
KR10-2019-0111292 2019-09-09

Related Child Applications (2)

Application Number Title Priority Date Filing Date
US17/043,897 A-371-Of-International US12027704B2 (en) 2018-09-20 2019-09-10 Sulfur-carbon composite and lithium secondary battery comprising same
US18/731,673 Continuation US20240332528A1 (en) 2018-09-20 2024-06-03 Sulfur-carbon composite and lithium secondary battery comprising same

Publications (1)

Publication Number Publication Date
WO2020060097A1 true WO2020060097A1 (en) 2020-03-26

Family

ID=69887507

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2019/011707 WO2020060097A1 (en) 2018-09-20 2019-09-10 Sulfur-carbon composite and lithium secondary battery comprising same

Country Status (1)

Country Link
WO (1) WO2020060097A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103474633A (en) * 2012-06-07 2013-12-25 中国人民解放军63971部队 Carbon-sulfur-shell matter composite material having network dual-core shell structure and preparation method thereof
KR20140122886A (en) * 2013-04-11 2014-10-21 한국과학기술원 Electrode for lithum-sulphur secondary battery using composite of polymer nanofiber, aluminum thin film, carbon nanotube and sulphur, and fabricating method thereof
US20170125802A1 (en) * 2015-10-28 2017-05-04 The Regents Of The University Of California Methods for making conformational conductive coated materials
KR20180112636A (en) 2017-04-04 2018-10-12 고한용 Exothermic body band and exothermic under-shirt with spandex fabric made in one piece ,and exothermic pad with spandex fabric and other fabrics made of split and a method fixing the same
KR20190111292A (en) 2018-03-22 2019-10-02 포항공과대학교 산학협력단 Dielectric based metasurface hologram device and manufacturing method thereof and display device having the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103474633A (en) * 2012-06-07 2013-12-25 中国人民解放军63971部队 Carbon-sulfur-shell matter composite material having network dual-core shell structure and preparation method thereof
KR20140122886A (en) * 2013-04-11 2014-10-21 한국과학기술원 Electrode for lithum-sulphur secondary battery using composite of polymer nanofiber, aluminum thin film, carbon nanotube and sulphur, and fabricating method thereof
US20170125802A1 (en) * 2015-10-28 2017-05-04 The Regents Of The University Of California Methods for making conformational conductive coated materials
KR20180112636A (en) 2017-04-04 2018-10-12 고한용 Exothermic body band and exothermic under-shirt with spandex fabric made in one piece ,and exothermic pad with spandex fabric and other fabrics made of split and a method fixing the same
KR20190111292A (en) 2018-03-22 2019-10-02 포항공과대학교 산학협력단 Dielectric based metasurface hologram device and manufacturing method thereof and display device having the same

Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
GAO, HONG ET AL.: "Facile preparation of an ultrathin sulfur-wrapped polyaniline nanofiber composite with a core-shell structure as a high performance cathode material for lithium-sulfur batteries", JOURNAL OF MATERIALS CHEMISTRY A, vol. 3, 5 March 2015 (2015-03-05), pages 7215 - 7218, XP055693417 *
GUO-CHUN LI ET AL., ADVANCED ENERGY MATERIALS, vol. 2, 2012, pages 1238 - 1245
J. MATER. CHEM. A, vol. 2, 2014, pages 18613 - 18623
JIAXING HUANG ET AL.: "Nanofiber Formation in the Chemical Polymerization of Aniline: A Mechanistic Study", ANGEW. CHEM. INT. ED., vol. 43, 2004, pages 5817 - 5821, XP055586268, DOI: 10.1002/anie.200460616
JUN JIN ET AL., SOLID STATE IONICS, vol. 262, 2014, pages 170 - 173
WANG, JUNKAI ET AL.: "C-S@PANI composite with a polymer spherical network structure for high performance lithium-sulfur batteries", PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 18, 5 November 2015 (2015-11-05), pages 261 - 266, XP004215999 *

Similar Documents

Publication Publication Date Title
WO2018034526A1 (en) Anode comprising multiple protective layers, and lithium secondary battery comprising same
WO2018208034A1 (en) Method for manufacturing negative electrode for lithium secondary battery
WO2018012694A1 (en) Lithium secondary battery having lithium metal formed on cathode and manufacturing method therefor
WO2019088672A1 (en) Anode active material for electrochemical device, anode comprising same anode active material, and electrochemical device comprising same anode
WO2020055183A1 (en) Anode for lithium secondary battery and method for manufacturing lithium secondary battery
WO2018169247A2 (en) Anode for lithium secondary battery, production method therefor, and lithium secondary battery comprising same
WO2010053328A2 (en) Positive active material with improved high voltage characteristics
WO2016032240A1 (en) Negative electrode active material having double coating layers, method for preparing same, and lithium secondary battery comprising same
WO2018212481A1 (en) Method for manufacturing anode for lithium secondary battery
WO2018208035A1 (en) Method for manufacturing lithium secondary battery
WO2020185014A1 (en) Negative electrode and secondary battery comprising same
WO2020085823A1 (en) Method for manufacturing anode for lithium secondary battery
WO2018016737A1 (en) Lithium secondary battery comprising cathode active material for synthesizing lithium cobalt oxide, and manufacturing method therefor
WO2020262890A1 (en) Anode and secondary battery comprising same
WO2020162708A1 (en) Anode and lithium secondary battery comprising same
WO2019221410A1 (en) Negative electrode including electrode protective layer, and lithium secondary battery employing same
WO2021025349A1 (en) Anode, manufacturing method therefor, and secondary battery comprising same
WO2020149681A1 (en) Anode and secondary battery comprising anode
WO2020159263A1 (en) Method for manufacturing anode for secondary battery
WO2018062883A2 (en) Anode for lithium secondary battery comprising mesh-shaped insulating layer, and lithium secondary battery comprising same
WO2020060079A1 (en) Anode for lithium secondary battery and lithium secondary battery comprising same
WO2021251663A1 (en) Anode and secondary battery comprising same
WO2020231087A1 (en) Method for manufacturing anode
US12027704B2 (en) Sulfur-carbon composite and lithium secondary battery comprising same
WO2022164212A1 (en) Separator for lithium secondary battery and manufacturing method therefor

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19863939

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2021503690

Country of ref document: JP

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 2019863939

Country of ref document: EP

Effective date: 20201007

NENP Non-entry into the national phase

Ref country code: DE