WO2018236046A1 - Lithium-sulfur battery - Google Patents

Lithium-sulfur battery Download PDF

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Publication number
WO2018236046A1
WO2018236046A1 PCT/KR2018/005189 KR2018005189W WO2018236046A1 WO 2018236046 A1 WO2018236046 A1 WO 2018236046A1 KR 2018005189 W KR2018005189 W KR 2018005189W WO 2018236046 A1 WO2018236046 A1 WO 2018236046A1
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Prior art keywords
lithium
sulfur battery
sulfur
radical
separator
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PCT/KR2018/005189
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French (fr)
Korean (ko)
Inventor
김기현
김수현
양두경
진선미
이창훈
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주식회사 엘지화학
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Priority claimed from KR1020180051030A external-priority patent/KR102320325B1/en
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to JP2019568206A priority Critical patent/JP7065893B2/en
Priority to EP18821205.4A priority patent/EP3624223B1/en
Priority to CN201880035323.0A priority patent/CN110679010B/en
Priority to US16/624,750 priority patent/US11545720B2/en
Publication of WO2018236046A1 publication Critical patent/WO2018236046A1/en

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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/38Selection of substances as active materials, active masses, active liquids of elements or alloys
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/62Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Definitions

  • the present invention relates to a lithium-sulfur battery including a radical compound having a nitroxyl radical functional group, and more particularly, To a lithium-sulfur battery in which the diffusion of lithium polysulfide is suppressed.
  • a lithium-sulfur (Li-S) battery is a secondary battery in which a sulfur-based material having a sulfur-sulfur bond is used as a cathode active material and lithium metal is used as an anode active material.
  • Sulfur the main material of the cathode active material, is very rich in resources, has no toxicity, and has a low atomic weight.
  • the theoretical energy density of the lithium-sulfur battery is 1675 mAh / g-sulfur and the theoretical energy density is 2,600 Wh / kg.
  • Ni-MH battery 450 Wh / , which is the most promising among the batteries that have been developed to date, because it is much higher than the FeS battery (480Wh / kg), Li-MnO 2 battery (1,000Wh / kg) and Na-S battery (800Wh / kg).
  • lithium polysulfide (Li 2 S x , usually x> 4) It melts easily. The lithium polysulfide dissolved in the electrolytic solution diffuses away from the anode where the lithium polysulfide is generated due to the difference in the concentration. Thus, the lithium polysulfide eluted from the anode is lost outside the positive electrode reaction region, and it is impossible to perform the stepwise reduction to lithium sulfide (Li 2 S).
  • the lithium polysulfide existing in a dissolved state from the anode and the cathode is not able to participate in the charge-discharge reaction of the battery, the amount of the sulfur material participating in the electrochemical reaction at the anode is reduced, which is a major factor in reducing the charge capacity and energy of the battery.
  • the lithium polysulfide diffused into the cathode causes a problem of corrosion of the lithium metal cathode because it reacts directly with lithium and is fixed in the form of Li 2 S on the surface of the cathode.
  • Patent Document 1 Korean Patent Laid-Open No. 10-2016-0146844 (2016.12.21), "lithium sulfur solid electrochemical cell having a long cycle life"
  • Non-Patent Document 1 Hongwei Chena, Changhong Wanga, Yafei Daib, Jun Gea, Wei Lua and Liwei Chen, In-situ activated polycation as a multifunctional additive for Li-S batteries. Nano Energy. 2016. 26. 43-49
  • the lithium-sulfur battery has a problem that capacity and life characteristics of the battery are deteriorated due to lithium polysulfide which is eluted and diffused from the anode.
  • the present inventors have found that a radical compound having a nitroxyl radical functional group, which is a stable free radical molecule, is effective in adsorbing lithium polysulfide, thereby completing the present invention.
  • an object of the present invention is to improve the capacity and lifetime characteristics of a battery by providing a separation membrane containing the polysulfide adsorption layer.
  • Still another object of the present invention is to provide a lithium-sulfur battery including the separator.
  • a positive electrode comprising a sulfur-carbon composite
  • a cathode arranged opposite to the anode
  • a lithium-sulfur battery including a separator interposed between the positive electrode and the negative electrode,
  • the separation membrane comprises a separation membrane body; And a lithium polysulfide adsorption layer formed on at least one side of the separator main body,
  • the adsorbent layer comprises a radical compound having a nitroxyl radical functional group.
  • the present invention also provides a method for producing a lithium-sulfur battery
  • the separation membrane comprising: i) preparing a separation membrane body; ii) preparing a solution by mixing a radical compound having a nitroxyl radical portion in a solvent; iii) coating the solution on at least one side of the membrane body; And iv) drying the coated separator to form a lithium polysulfide adsorption layer.
  • the method of manufacturing a lithium-sulfur battery includes:
  • the lithium polysulfide eluted from the positive electrode is adsorbed by the radical compound having the nitroxyl radical functional group, thereby preventing elution and diffusion of the lithium polysulfide, thereby improving the capacity and lifetime characteristics of the battery.
  • FIG. 1 is a cross-sectional view of a lithium-sulfur battery including a separator having an adsorption layer of lithium sulfide.
  • TEM 2 is a scanning electron microscope (TEM) of a separator coated with poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-ylmethacrylate (PTMA)), a radical compound having a nitroxyl radical functional group SEM) images.
  • TEM scanning electron microscope
  • SEM scanning electron microscope
  • Example 4 is a graph showing the battery life characteristics of the specific discharging capacity and the coulombic efficiency according to Example 1 and Comparative Example 1 of the present invention.
  • 5 is a graph showing the discharge capacity of the lithium-sulfur battery after 10 cycles.
  • 6 is a graph showing the discharge capacity of the lithium-sulfur battery after 30 cycles.
  • Example 8 is a graph showing the battery lifetime characteristics of specific discharging capacity and coulombic efficiency according to Example 1 and Comparative Example 2 of the present invention.
  • Example 9 is a graph showing the battery lifetime characteristics of specific discharging capacity and coulombic efficiency according to Example 1 and Comparative Example 3 of the present invention.
  • the present invention relates to a lithium polysulfide adsorption layer containing a radical compound having a nitrosyl radical functional group on at least one surface of a separator main body to prevent diffusion of lithium polysulfide and improve the capacity and lifetime of the battery, Thereby providing a separation membrane.
  • At least one surface of the separator main body is one surface or both surfaces necessarily including a surface facing the anode when assembling the electrode.
  • the radical compound having a nitroxyl radical functional group may be located on the surface or in the interior of the separation membrane and is preferably positioned on the surface of the separation membrane facing the anode in order to prevent the diffusion of lithium polysulfide produced in the anode of the lithium- can do.
  • the lithium-sulfur battery includes a cathode 200 and a cathode 300, and an electrolyte 400 and a separator 100 interposed therebetween.
  • a separation membrane 100 in which a separation membrane body 110 and an adsorption layer 120 are sequentially laminated.
  • the adsorption layer 120 may be formed on one side of the separation membrane body 110, and may be formed on both sides if necessary.
  • the separator main body 110 is not particularly limited in the present invention, and can be used without any particular limitation as long as it is physically separated from the electrode, has an electrolyte and ion permeability, and is used as a conventional separator.
  • the nonconductive or insulating material it is preferable that the material has low resistance to ion movement of the electrolytic solution and excellent electrolytic solution impregnation ability.
  • a porous polymer film such as a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer and an ethylene / methacrylate copolymer
  • a nonwoven fabric made of conventional porous nonwoven fabric such as high melting point glass fiber or polyethylene terephthalate fiber can be used, but the present invention is not limited thereto .
  • the radical compound having a nitroxyl radical functional group contained in the adsorption layer 120 means a structure having a functional group represented by the following formula (1).
  • R 1 and R 2 may be aliphatic, aromatic, hydroxyl, alkoxy, aldehyde, carboxyl, amino, or a combination thereof, R 1 and R 2 may be different or the same.
  • radical compound provided in the present invention may be a polymer having an intramolecular nitrosyl radical functional group.
  • the polymer may be polymerized from a monomer containing any one functional group selected from the group consisting of (meth) acrylate, acrylonitrile, anhydride, styrene, epoxy, isocyanate and vinyl groups.
  • the polymer may be selected from the group consisting of poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-ylmethacrylate (PTMA), poly (2,2,6,6-tetramethyl- (PTVE), poly (TEMPO-substituted norbornene) (PTN), poly (2,2,5,5-tetramethylpyrrolidine-1-oxyl-3-yl ethylene oxide PTEB), poly (2,3-bis (2,2,6,6-tetramethylpiperidine-1-oxyl-4-oxyphenyl) -5- (PTAm), and combinations thereof.
  • the TEMPO may be at least one selected from the group consisting of (2,2,6,6-tetramethylpiperidin-1-yl) oxyl compound .
  • the radical compound having a nitroxyl radical functional group can form an adsorption layer by itself as a polymer
  • the content of the radical compound having a nitroxyl radical functional group in the present invention may be 80 wt% or more of the total weight of the adsorbent layer have.
  • the following formula (2) represents PTMA which is a kind of polymer formed by the polymerization reaction, which contains the nitroxyl radical functional group in the molecule provided by the present invention.
  • the monomer type of the PTMA is TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl) oxyl) compound, which can be attached to a polymer backbone to form PTMA.
  • PTMA which is a radical compound proposed in the present invention can explain the stability of PTMA through the following formula (3) as a relatively stable compound by the phenomenon of dissociation of electrons from nitrogen to oxygen.
  • the PTMA in the state (B) is changed into the activated cation in the state (C), and the PTMA in the state (C) is changed to the polysulfide In 4 As shown in FIG.
  • PTMA which is a polymer is used. Since PTMA has a high molecular weight, it is advantageous that it can be coated on a separator without being dissolved in an electrolyte.
  • the adsorption layer 120 of the present invention may include a conductive material together with the above-described radical compound having a nitrosyl radical functional group in order to impart additional electrical conductivity to the lithium-sulfur battery.
  • sulfur which is a positive electrode active material of a lithium-sulfur battery, does not have conductivity by itself, it is generally made of a composite of a conductive carbon material and an anode 200 of a sulfur-carbon composite.
  • the adsorption layer 120 of the present invention may include a conductive material to provide additional sulfur reduction sites in addition to the anode reaction sites.
  • the conductive material of the adsorption layer 120 may additionally provide a reduction reaction site of the adsorbed lithium polysulfide 20 to increase the electrode efficiency.
  • the conductive material included in the adsorption layer 120 according to the present invention may be selected from the group consisting of a carbon-based conductive material, a conductive polymer, and a combination thereof.
  • the carbon-based conductive material is not limited in its kind but may be graphite such as natural graphite, artificial graphite, expanded graphite, Graphene, Super-P and Super-C. Active black carbon black, Channel black, Denka black, Furnace black, Thermal black, Contact black, Lamp black, Carbon black such as acetylene black; Carbon nanotubes such as a carbon fiber, a carbon nanotube (CNT), and a fullerene, and combinations thereof.
  • the carbon nanotube may include a super- Can be used.
  • the conductive polymer may be selected from the group consisting of polyaniline, polypyrrole, polythiophene, polyazulene, polypyridine, polyindole, polycarbazole, Polycarbazole, Polyazine, Polyquinone, Polyacetylene, Polyselenophene, Polytellurophene, Poly-p-phenylene, Poly And may include one selected from the group consisting of polyphenylene vinylene, polyphenylene sulfide, polyethylene dioxythiophene, polyethylene glycol, and combinations thereof.
  • the weight ratio of the radical compound having a nitrosyl radical functional group and the conductive material is controlled within a range of 3: 1 to 7: 1 for the above-described lithium polysulfide diffusion preventing effect and the conductivity imparting effect for providing the lithium polysulfide reduction reaction site It is possible. If an excess amount of a radical compound having a nitrosyl radical functional group is used in excess of the above-mentioned range, it acts as a resistive layer to deteriorate battery performance. On the contrary, when an excess amount of conductive material is used, a radical having a nitrosyl radical functional group It is difficult to secure the effect due to the radical compound because the content of the compound is decreased. Therefore, it is preferable to appropriately use the compound in the above range.
  • the adsorption layer 120 may be formed on the separation membrane body 110 to have a thickness of 0.1 to 10 ⁇ , preferably 0.1 to 5 ⁇ , in order to secure the above-mentioned effect. If the thickness is less than the above range, the effect of adsorbing lithium polysulfide is insufficient. On the other hand, if the thickness exceeds the above range, the lithium ion conductivity is lowered to cause problems in electrode performance. Therefore, .
  • a cathode comprising the sulfur-carbon composite of the present invention; A cathode arranged opposite to the anode; And a separator interposed between the anode and the cathode.
  • the lithium-sulfur battery includes tetramethylpiperidine N-oxyl in a part of the separator. At this time, the tetramethylpiperidine N-oxyl contained in the separator may be dissolved in the electrolyte during discharging and charging of the battery.
  • the separation membrane of the lithium-sulfur battery according to the present invention comprises i) preparing a separator main body; ii) preparing a solution by mixing a radical compound having a nitroxyl radical portion in a solvent; iii) coating the solution on at least one side of the membrane body; And iv) drying the coated separator to form a lithium polysulfide adsorption layer.
  • the separation membrane body 110 is not particularly limited in the present invention, and any one of the separation membrane bodies described above can be selected, and it is possible to purchase or use a commercially available separation membrane.
  • a radical compound having a nitrosyl radical functional group is dispersed in a predetermined solvent to prepare a radical compound solution.
  • a solvent which can uniformly disperse the radical compound and is easily evaporated and can be dried.
  • NMP N-methyl-2-pyrrolidone
  • acetonitrile acetonitrile
  • methanol ethanol
  • Tetrahydrofuran water
  • isopropyl alcohol and the like
  • the mixing for the preparation of the radical compound solution may be carried out by a conventional method using a conventional mixer such as a paste mixer, a high-speed shear mixer, a homomixer or the like.
  • the prepared solution is coated on one surface of the separator main body 110.
  • one surface of the separator main body 110 is one surface of the separator main body 110 which is assembled opposite to the anode 200 at the time of later electrode assembly.
  • a method of coating the slurry for example, a doctor blade coating, a dip coating, a gravure coating, a slit die coating, a spin coating, a comma
  • a reverse coating method, a screen coating method, a cap coating method, and the like, may be used as a method of coating the slurry.
  • the drying process is a process of removing the solvent and moisture in the adsorption layer 120 coated on the separation membrane.
  • the drying temperature and time may vary depending on the solvent used. Generally, the drying process is performed in a vacuum oven at 50 to 200 ° C within 48 hours Drying is preferred.
  • the radical compound having a nitrosyl radical functional group according to the present invention can form an adsorption layer by itself as the polymer, the content of the radical compound is not less than 80% by weight of the total weight of the adsorption layer .
  • a positive electrode comprising a sulfur-carbon composite; A cathode arranged opposite to the anode; And a separator interposed between the anode and the cathode, wherein the separator comprises a separator main body; And a lithium polysulfide adsorbent layer formed on at least one side of the separator main body, wherein the adsorbent layer comprises a radical compound having a nitrosyl radical functional group.
  • the separation membrane 100 may be interposed between the anode 200 and the cathode 300, and may be a separator of the lithium-sulfur battery, At this time, when the adsorption layer 120 is coated on only one surface, the adsorption layer 120 is preferably arranged to face the anode 200 in order to prevent diffusion of lithium polysulfide.
  • the anode 200 may include a sulfur element (S 8 ) as a cathode active material, a sulfur-based compound, or a mixture thereof. Since the sulfur element alone does not have electrical conductivity, the anode 200 may be used in combination with a conductive material .
  • a sulfurized poly-acrylonitrile (SPAN) anode with good lifetime characteristics can be used as the anode of the lithium-sulfur battery.
  • the average operating voltage of the SPAN anode is 1.7 V and the energy Since the density is low and the content of sulfur in the SPAN anode is also about 40% smaller than that in the sulfur-carbon composite anode, the anode of the lithium-sulfur battery is limited to the anode of the sulfur-carbon composite.
  • the conductive material may be porous. Therefore, any conductive material having porosity and conductivity may be used without limitation, and for example, a carbon-based material having porosity may be used. Examples of the carbon-based material include carbon black, graphite, graphene, activated carbon, carbon fiber, and carbon nanotube (CNT). Further, metallic fibers such as metal mesh; Metallic powder such as copper, silver, nickel, and aluminum; Or an organic conductive material such as a polyphenylene derivative can also be used. The conductive materials may be used alone or in combination.
  • the negative electrode 300 is a negative electrode active material that can reversibly intercalate or deintercalate lithium ions Li + , a material capable of reversibly reacting with lithium ions to form a lithium-containing compound, lithium A metal or a lithium alloy can be used.
  • the material capable of reversibly storing or releasing lithium ions (Li &lt ; + & gt ; ) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof.
  • the material capable of reacting with the lithium ion (Li &lt ; + & gt ; ) to reversibly form a lithium-containing compound may be, for example, tin oxide, titanium nitride or silicon.
  • the lithium alloy includes, for example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg) Ca, Sr, Ba, Ra, Al, Si, and Sn.
  • the metal may be an alloy of a metal selected from the group consisting of Ca, Sr, Ba,
  • Inactive sulfur is sulfur in which sulfur can not participate in the electrochemical reaction of the anode after various electrochemical or chemical reactions.
  • Inactive sulfur formed on the surface of the lithium anode is a protective film of the lithium anode layer as well.
  • the electrolyte 400 impregnated into the anode 200, the cathode 300 and the separator 100 is a non-aqueous electrolyte containing a lithium salt and is composed of a lithium salt and an electrolyte.
  • the organic solid electrolyte and the inorganic solid electrolyte Etc. may be used.
  • the lithium salt of the present invention can be dissolved in a non-aqueous organic solvent, for example, LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiB (Ph) 4 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, LiSO 3 CH 3, LiSO 3 CF 3, LiSCN, LiC (CF 3 SO 2) 3, LiN (CF 3 SO 2) 2, LiNO 3, chloroborane lithium , Lower aliphatic carboxylic acid lithium, lithium 4-phenylborate, and imide.
  • a non-aqueous organic solvent for example, LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiB (Ph) 4 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, LiSO 3 CH 3, Li
  • the concentration of the lithium salt may be 0.2 to 4 M according to various factors such as the precise composition of the electrolyte mixture, the solubility of the salt, the conductivity of the dissolved salt, the charging and discharging conditions of the battery, the working temperature and other factors known to the lithium battery To 0.3 M, more specifically 0.3 M to 1.5 M, for example. If it is used at less than 0.2 M, the conductivity of the electrolyte may be lowered and electrolyte performance may be deteriorated. If it is used in excess of 4 M, the viscosity of the electrolyte may increase and the mobility of lithium ion (Li + ) may be decreased.
  • non-aqueous organic solvent of the present invention examples include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, di Ethyl carbonate, ethyl methyl carbonate, gamma-butylolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, Diethyl ether, formamide, dimethyl formamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane , A dioxolane derivative, an aprotic organic solvent such as sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionat
  • organic solid electrolyte examples include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer including a group can be used.
  • a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer including a group can be used.
  • Examples of the inorganic solid electrolyte of the present invention include Li 3 N, LiI, Li 5 NI 2 , Li 3 N-LiI-LiOH, LiSiO 4 , LiSiO 4 -LiI-LiOH, Li 2 SiS 3 , Li 4 SiO 4 , Nitrides, halides and sulfates of Li such as Li 4 SiO 4 -LiI-LiOH and Li 3 PO 4 -Li 2 S-SiS 2 can be used.
  • the electrolyte of the present invention may be added to the electrolyte for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, hexaphosphoric triamide, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, .
  • a halogen-containing solvent such as carbon tetrachloride, ethylene trifluoride or the like may be further added to impart nonflammability.
  • carbon dioxide gas may be further added.
  • the lithium-sulfur battery according to the present invention may include additives commonly used in the lithium-sulfur battery field, and preferably, it may be vinylene carbonate (VC) or ethylene carbonate (EC).
  • VC vinylene carbonate
  • EC ethylene carbonate
  • the separator 100 cut to a predetermined size corresponding to the positive electrode plate and the negative electrode plate is interposed between the positive electrode plate and the negative electrode plate obtained by cutting the positive electrode 200 and the negative electrode 300 to a predetermined size, Can be produced.
  • two or more positive plates and negative plates may be arranged on the separator sheet so that the positive electrode 200 and the negative electrode 300 face each other with the separator 100 sheet therebetween, or the two or more positive and negative plates may be stacked with the separator interposed therebetween Stacked and folded electrode assemblies can be manufactured by arranging two or more unit cells on the separator sheet, winding the separator sheet, or bending the separator sheet to the size of the electrode plate or unit cell.
  • the battery pack including the lithium-sulfur battery includes an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV) And can be used as a power source of a storage device.
  • EV electric vehicle
  • HEV hybrid electric vehicle
  • PHEV plug-in hybrid electric vehicle
  • PTMA was dissolved in N-methyl-2-pyrrolidone (NMP) to prepare a 1 wt% PTMA solution.
  • NMP N-methyl-2-pyrrolidone
  • the solution was coated on a polypropylene separator having a thickness of 20 ⁇ m using a bar coater, followed by vacuum drying to prepare a 0.5 ⁇ m PTMA-coated separator.
  • SBR is styrene butadiene rubber
  • CMC is carboxymethyl cellulose.
  • Lithium foil having a thickness of 150 mu m was used as a cathode.
  • 70 ⁇ l of an electrolytic solution obtained by mixing 1M LiN (CF 3 SO 2 ) 2 dissolved in dimethoxyethane and dioxolane in a volume ratio of 1: 1 was introduced into the separator prepared in the above Preparation Example, To produce an electrode assembly.
  • the electrode assembly was housed in a battery case to prepare a lithium-sulfur battery coin cell.
  • a separator was prepared in the same manner as in the above preparation example, except that a polypropylene film having a thickness of 20 ⁇ in which no PTMA solution was coated was used as a separator instead of the separator in which the PTFE solution was coated on the polypropylene.
  • a coin cell was fabricated in the same manner as in Example 1, except that the separation membrane of Comparative Production Example 1 was used instead of the separation membrane in which the PTMA solution was coated on the polypropylene in Example 1.
  • PTMA was not coated on the separator but mixed with 70 wt% of a cathode active material prepared by mixing carbon and sulfur at a weight ratio of 9: 1, 20 wt% of Denka black as a conductive material and 9 wt% of SBR / CMC (weight ratio of 1: 1) And 1% by weight of PTMA were added to DI water to prepare a positive electrode slurry and then coated on an aluminum current collector to prepare a positive electrode.
  • a lithium-sulfur battery coin cell was prepared in the same manner as in Example 1, .
  • Example 2 In the same manner as in Example 1, except that the PTFE-coated polypropylene separator membrane in Example 1 was used, and a separator membrane impregnated with PTMA to the interior of the separator membrane was carried by PTMA solution for 1 minute, Cells were prepared.
  • the separation membrane surfaces of the preparation examples and comparative preparation examples were confirmed by scanning electron microscopy (SEM).
  • the rate of charge / discharge was evaluated at 0.1C for the initial 3 cycles, then at 0.2C for 3 cycles and then at 0.5C (evaluated at 0.2C for 3 cycles every 10 cycles)
  • Example 1 which is a lithium-sulfur battery using a PTMA-coated separator, exhibits remarkably improved capacity retention and coulon efficiency as compared with Comparative Example 1.
  • Example 8 shows that the capacity retention rate and the coulombic efficiency of the battery of Comparative Example 2, in which the PTMA is not coated on the separator but applied to the binder of the lithium-sulfur battery, are lower than those of Example 1.
  • the lithium-sulfur battery of Example 1 exhibited a better 890 mAh / g level than Comparative Example 1 after 10 cycles, 30 cycles, and 60 cycles due to the adsorption effect of polysulfide by PTMA Respectively.
  • the lithium-sulfur battery of the present invention suppresses the diffusion of polysulfide, thereby improving electrode loading and initial discharge capacity, and ultimately increasing the energy density of the lithium-sulfur battery.
  • the lithium-sulfur battery is preferably applicable as a high-density battery or a high-performance battery.

Abstract

The present invention relates to lithium-sulfur battery including a separation membrane in which an adsorption layer including a radical compound having a nitroxyl radical region is formed, and more particularly, to a lithium-sulfur battery in which an adsorption layer, which includes a conductive material and a radical compound having a nitroxyl radical region, is applied on a surface of a separation membrane to suppress the elution of lithium polysulfide. In a lithium-sulfur battery according to the present invention, not only is the elution and diffusion of lithium polysulfide that elutes from a positive electrode prevented through the adsorption by a radical compound that is a stable radical compound having a nitroxyl radical region, but positive electrode active material reaction sites are provided by imparting additional electrical conductivity. Accordingly, the capacity and lifespan properties of the battery are enhanced.

Description

리튬-황 전지Lithium-sulfur battery
본 출원은 2017년 06월 20일자 한국 특허 출원 제10-2017-0077983호 및 2018년 05월 03일자 한국 특허 출원 제10-2018-0051030호에 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. 10-2017-0077983 dated June 20, 2017, and Korean Patent Application No. 10-2018-0051030 dated May 03, 2018, All of which are incorporated herein by reference.
본 발명은 니트록실 라디칼 관능기를 가지는 라디칼 화합물을 포함하는 흡착층이 형성된 리튬-황 전지에 관한 것으로, 보다 상세하게는 분리막의 적어도 일면에 니트록실 라디칼 관능기를 가지는 라디칼 화합물을 포함하는 코팅층을 적용하여 리튬 폴리설파이드의 확산이 억제된 리튬-황 전지에 관한 것이다.More particularly, the present invention relates to a lithium-sulfur battery including a radical compound having a nitroxyl radical functional group, and more particularly, To a lithium-sulfur battery in which the diffusion of lithium polysulfide is suppressed.
최근 전자제품, 전자기기, 통신기기 등의 소형 경량화가 급속히 진행되고 있으며, 환경 문제와 관련하여 전기 자동차의 필요성이 크게 대두됨에 따라 이들 제품의 동력원으로 사용되는 이차전지의 성능 개선에 대한 요구도 증가하는 실정이다. 그 중 리튬 이차전지는 고 에너지밀도 및 높은 표준전극 전위 때문에 고성능전지로서 상당한 각광을 받고 있다.In recent years, miniaturization and weight reduction of electronic products, electronic devices, and communication devices are rapidly proceeding. As the necessity of electric automobiles has been greatly increased with respect to environmental problems, there has been an increase in demand for performance improvement of secondary batteries used as power sources for these products . Among them, lithium secondary batteries are attracting considerable attention as high performance batteries due to high energy density and high standard electrode potential.
특히 리튬-황(Li-S) 전지는 S-S 결합(Sulfur - sulfur bond)을 갖는 황 계열물질을 양극 활물질로 사용하고, 리튬 금속을 음극 활물질로 사용하는 이차전지이다. 양극 활물질의 주재료인 황은 자원이 매우 풍부하고, 독성이 없으며, 낮은 원자당 무게를 가지고 있는 장점이 있다. 또한 리튬-황 전지의 이론 방전용량은 1675mAh/g-sulfur이며, 이론 에너지밀도가 2,600Wh/kg로서, 현재 연구되고 있는 다른 전지시스템의 이론 에너지밀도(Ni-MH 전지: 450Wh/kg, Li-FeS 전지: 480Wh/kg, Li-MnO2 전지: 1,000Wh/kg, Na-S 전지: 800Wh/kg)에 비하여 매우 높기 때문에 현재까지 개발되고 있는 전지 중에서 가장 유망한 전지이다.In particular, a lithium-sulfur (Li-S) battery is a secondary battery in which a sulfur-based material having a sulfur-sulfur bond is used as a cathode active material and lithium metal is used as an anode active material. Sulfur, the main material of the cathode active material, is very rich in resources, has no toxicity, and has a low atomic weight. The theoretical energy density of the lithium-sulfur battery is 1675 mAh / g-sulfur and the theoretical energy density is 2,600 Wh / kg. The theoretical energy density (Ni-MH battery: 450 Wh / , Which is the most promising among the batteries that have been developed to date, because it is much higher than the FeS battery (480Wh / kg), Li-MnO 2 battery (1,000Wh / kg) and Na-S battery (800Wh / kg).
리튬-황 전지의 방전 반응 중 음극(Anode)에서는 리튬의 산화 반응이 발생하고, 양극(Cathode)에서는 황의 환원 반응이 발생한다. 방전 전의 황은 환형의 S8 구조를 가지고 있는데, 환원 반응(방전) 시 S-S 결합이 끊어지면서 S의 산화수가 감소하고, 산화 반응(충전) 시 S-S 결합이 다시 형성되면서 S의 산화수가 증가하는 산화-환원 반응을 이용하여 전기 에너지를 저장 및 생성한다. 이런 반응 중 황은 환형의 S8에서 환원 반응에 의해 선형 구조의 리튬 폴리설파이드(Lithium polysulfide, Li2SX, x = 8, 6, 4, 2)로 변환되게 되며, 결국 이러한 리튬 폴리설파이드가 완전히 환원되면 최종적으로 리튬 설파이드(Lithium sulfide, Li2S)가 생성되게 된다. 각각의 리튬 폴리설파이드로 환원되는 과정에 의해 리튬-황 전지의 방전 거동은 리튬 이온전지와는 달리 단계적으로 방전 전압을 나타내는 것이 특징이다.During the discharge reaction of the lithium-sulfur battery, an oxidation reaction of lithium occurs at the anode and a sulfur reduction reaction occurs at the cathode. Sulfur before discharging has an annular S 8 structure. When the SS bond is cut off during the reduction reaction (discharging), the oxidation number of S decreases, and when the oxidation reaction (charging) The reduction reaction is used to store and generate electrical energy. During this reaction, the sulfur is converted to a linear polysulfide (Li 2 S x , x = 8, 6, 4, 2) by a reduction reaction at the cyclic S 8 , When it is reduced, lithium sulfide (Li 2 S) is finally produced. The discharge behavior of the lithium-sulfur battery by the process of reducing to each lithium polysulfide characterizes the discharge voltage stepwise unlike the lithium ion battery.
Li2S8, Li2S6, Li2S4, Li2S2 등의 리튬 폴리설파이드 중에서, 특히 황의 산화수가 높은 리튬 폴리설파이드(Li2SX, 보통 x > 4)는 친수성의 전해액에 쉽게 녹는다. 전해액에 녹은 리튬 폴리설파이드는 농도 차에 의해서 리튬 폴리설파이드가 생성된 양극으로부터 먼 쪽으로 확산되어 간다. 이렇게 양극으로부터 용출된 리튬 폴리설파이드는 양극 반응 영역 밖으로 유실되어 리튬 설파이드(Li2S)로의 단계적 환원이 불가능하다. 즉, 양극과 음극을 벗어나 용해된 상태로 존재하는 리튬 폴리설파이드는 전지의 충·방전 반응에 참여할 수 없게 되므로, 양극에서 전기화학 반응에 참여하는 황 물질의 양이 감소하게 되고, 결국 리튬-황 전지의 충전 용량 감소 및 에너지 감소를 일으키는 주요한 요인이 된다.Among lithium polysulfides such as Li 2 S 8 , Li 2 S 6 , Li 2 S 4 , and Li 2 S 2 , lithium polysulfide (Li 2 S x , usually x> 4) It melts easily. The lithium polysulfide dissolved in the electrolytic solution diffuses away from the anode where the lithium polysulfide is generated due to the difference in the concentration. Thus, the lithium polysulfide eluted from the anode is lost outside the positive electrode reaction region, and it is impossible to perform the stepwise reduction to lithium sulfide (Li 2 S). That is, since the lithium polysulfide existing in a dissolved state from the anode and the cathode is not able to participate in the charge-discharge reaction of the battery, the amount of the sulfur material participating in the electrochemical reaction at the anode is reduced, Which is a major factor in reducing the charge capacity and energy of the battery.
뿐만 아니라 음극으로 확산한 리튬 폴리설파이드는 전해액 중에 부유 또는 침전되는 것 이외에도, 리튬과 직접 반응하여 음극 표면에 Li2S 형태로 고착되므로 리튬 금속 음극을 부식시키는 문제를 발생시킨다.In addition to being suspended or precipitated in the electrolyte solution, the lithium polysulfide diffused into the cathode causes a problem of corrosion of the lithium metal cathode because it reacts directly with lithium and is fixed in the form of Li 2 S on the surface of the cathode.
이러한 리튬 폴리설파이드의 용출을 최소화하기 위하여, 다양한 탄소 구조에 황 입자를 채워 넣는 복합체를 형성하는 양극 복합체의 모폴로지(Morphology)를 변형시키는 연구가 진행되고 있으나, 이러한 방법들은 제조방법이 복잡하고, 근본적인 문제를 해결하지 못하고 있는 실정이다.In order to minimize the dissolution of lithium polysulfide, studies have been conducted to modify the morphology of the anode composite forming a complex in which various carbon structures are filled with sulfur particles. However, these methods are complicated in manufacturing method, I have not been able to solve the problem.
[선행기술문헌][Prior Art Literature]
[특허문헌][Patent Literature]
(특허문헌 1) 대한민국 공개특허 제10-2016-0146844호(2016.12.21), "사이클 수명이 긴 리튬 황 고상 전기화학 셀"(Patent Document 1) Korean Patent Laid-Open No. 10-2016-0146844 (2016.12.21), "lithium sulfur solid electrochemical cell having a long cycle life"
(비특허문헌 1) Hongwei Chena, Changhong Wanga, Yafei Daib, Jun Gea, Wei Lua and Liwei Chen, In-situ activated polycation as a multifunctional additive for Li-S batteries. Nano Energy. 2016. 26. 43-49(Non-Patent Document 1) Hongwei Chena, Changhong Wanga, Yafei Daib, Jun Gea, Wei Lua and Liwei Chen, In-situ activated polycation as a multifunctional additive for Li-S batteries. Nano Energy. 2016. 26. 43-49
상술한 바와 같이, 리튬-황 전지는 양극으로부터 용출되어 확산되는 리튬 폴리설파이드로 인하여 전지의 용량 및 수명 특성이 저하되는 문제점이 있다. 이에 본 발명자들은 다양한 연구를 수행한 결과, 안정한 자유 라디칼 분자인 니트록실 라디칼 관능기를 가지는 라디칼 화합물이 리튬 폴리설파이드를 흡착하는데 효과가 있음을 확인하여 본 발명을 완성하였다.As described above, the lithium-sulfur battery has a problem that capacity and life characteristics of the battery are deteriorated due to lithium polysulfide which is eluted and diffused from the anode. As a result of various studies, the present inventors have found that a radical compound having a nitroxyl radical functional group, which is a stable free radical molecule, is effective in adsorbing lithium polysulfide, thereby completing the present invention.
따라서, 본 발명의 목적은 상기 폴리설파이드 흡착층을 포함하는 분리막을 제공함으로써, 전지의 용량 및 수명 특성을 향상시키는 것이다.Accordingly, an object of the present invention is to improve the capacity and lifetime characteristics of a battery by providing a separation membrane containing the polysulfide adsorption layer.
본 발명의 또 다른 목적은 상기 폴리설파이드 흡착층을 포함하는 분리막의 제조방법을 제공하는 것이다.It is still another object of the present invention to provide a process for producing a separation membrane comprising the polysulfide adsorption layer.
본 발명의 또 다른 목적은 상기 분리막을 포함하는 리튬-황 전지를 제공하는 것이다.Still another object of the present invention is to provide a lithium-sulfur battery including the separator.
상기 목적을 달성하기 위하여, 본 발명은 In order to achieve the above object,
황-탄소 복합체를 포함하는 양극; A positive electrode comprising a sulfur-carbon composite;
상기 양극과 대향 배치되는 음극; 및A cathode arranged opposite to the anode; And
상기 양극과 음극 사이에 개재되는 분리막을 포함하는 리튬-황 전지로서,A lithium-sulfur battery including a separator interposed between the positive electrode and the negative electrode,
상기 분리막은 분리막 본체; 및 상기 분리막 본체의 적어도 일면에 형성된 리튬 폴리설파이드 흡착층을 포함하고,Wherein the separation membrane comprises a separation membrane body; And a lithium polysulfide adsorption layer formed on at least one side of the separator main body,
상기 흡착층은 니트록실 라디칼 관능기를 가지는 라디칼 화합물을 포함하는 것을 특징으로 하는 리튬-황 전지를 제공한다.Wherein the adsorbent layer comprises a radical compound having a nitroxyl radical functional group.
또한 본 발명은 상기 리튬-황 전지의 제조방법에 있어서,The present invention also provides a method for producing a lithium-sulfur battery,
상기 분리막은, i) 분리막 본체를 준비하는 단계; ii) 니트록실 라디칼 부위를 가지는 라디칼 화합물을 용매에 혼합하여 용액을 제조하는 단계; iii) 상기 용액을 분리막 본체의 적어도 일면에 코팅하는 단계; 및 iv) 상기 코팅된 분리막을 건조하여 리튬 폴리설파이드 흡착층을 형성하는 단계;를 포함하여 제조되는 것을 특징으로 하는 리튬-황 전지의 제조방법을 제공한다.The separation membrane comprising: i) preparing a separation membrane body; ii) preparing a solution by mixing a radical compound having a nitroxyl radical portion in a solvent; iii) coating the solution on at least one side of the membrane body; And iv) drying the coated separator to form a lithium polysulfide adsorption layer. The method of manufacturing a lithium-sulfur battery includes:
본 발명에 따른 리튬-황 전지는 양극으로부터 용출되는 리튬 폴리설파이드를 니트록실 라디칼 관능기를 가지는 라디칼 화합물이 흡착하여, 리튬 폴리설파이드의 용출 및 확산을 방지함으로써 전지의 용량 및 수명 특성이 향상된다.In the lithium-sulfur battery according to the present invention, the lithium polysulfide eluted from the positive electrode is adsorbed by the radical compound having the nitroxyl radical functional group, thereby preventing elution and diffusion of the lithium polysulfide, thereby improving the capacity and lifetime characteristics of the battery.
도 1은 리튬 설파이드의 흡착층을 가지는 분리막을 포함하는 리튬-황 전지의 단면도이다.1 is a cross-sectional view of a lithium-sulfur battery including a separator having an adsorption layer of lithium sulfide.
도 2는 니트록실 라디칼 관능기를 가지는 라디칼 화합물인 폴리(2,2,6,6-테트라메틸-1-피페리디닐록시-4-일 메타아크릴레이트(PTMA)가 코팅된 분리막의 주사전자현미경(SEM) 이미지이다.2 is a scanning electron microscope (TEM) of a separator coated with poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-ylmethacrylate (PTMA)), a radical compound having a nitroxyl radical functional group SEM) images.
도 3은 PTMA가 코팅되지 않은 분리막의 주사전자현미경(SEM) 이미지이다.3 is a scanning electron microscope (SEM) image of a PTMA-uncoated membrane.
도 4는 본 발명의 실시예 1 및 비교예 1에 따른 비 방전 용량(Specific discharging capacity) 및 쿨롱 효율(Coulombic Efficiency)의 전지수명특성 효과를 나타낸 그래프이다.4 is a graph showing the battery life characteristics of the specific discharging capacity and the coulombic efficiency according to Example 1 and Comparative Example 1 of the present invention.
도 5는 리튬-황 전지의 10 사이클 후의 방전 용량을 나타낸 그래프이다.5 is a graph showing the discharge capacity of the lithium-sulfur battery after 10 cycles.
도 6는 리튬-황 전지의 30 사이클 후의 방전 용량을 나타낸 그래프이다.6 is a graph showing the discharge capacity of the lithium-sulfur battery after 30 cycles.
도 7은 리튬-황 전지의 60 사이클 후의 방전 용량을 나타낸 그래프이다.7 is a graph showing the discharge capacity of the lithium-sulfur battery after 60 cycles.
도 8은 본 발명의 실시예 1 및 비교예 2에 따른 비 방전 용량(Specific discharging capacity) 및 쿨롱 효율(Coulombic Efficiency)의 전지수명특성 효과를 나타낸 그래프이다.8 is a graph showing the battery lifetime characteristics of specific discharging capacity and coulombic efficiency according to Example 1 and Comparative Example 2 of the present invention.
도 9는 본 발명의 실시예 1 및 비교예 3에 따른 비 방전 용량(Specific discharging capacity) 및 쿨롱 효율(Coulombic Efficiency)의 전지수명특성 효과를 나타낸 그래프이다.9 is a graph showing the battery lifetime characteristics of specific discharging capacity and coulombic efficiency according to Example 1 and Comparative Example 3 of the present invention.
이하, 본 발명의 바람직한 실시예를 첨부된 예시 도면에 의거하여 상세히 설명한다. 이러한 도면은 본 발명을 설명하기 위한 일 구현예로서 여러 가지 상이한 형태로 구현될 수 있으며, 본 명세서에 한정되지 않는다.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. These drawings may be embodied in various different forms as an embodiment for explaining the present invention, and are not limited thereto.
리튬-황 전지용 분리막Separator for lithium-sulfur battery
본 발명은 리튬 폴리설파이드의 확산을 방지하여 전지의 용량과 수명 향상을 위하여, 분리막 본체의 적어도 일면에 니트록실 라디칼 관능기를 가지는 라디칼 화합물을 포함하는 리튬 폴리설파이드 흡착층 및 이를 포함하는 리튬-황 전지용 분리막을 제공한다. 상기 분리막 본체의 적어도 일면이란, 전극 조립시 양극과 대향하는 면을 반드시 포함하는 일면 또는 양면이다.The present invention relates to a lithium polysulfide adsorption layer containing a radical compound having a nitrosyl radical functional group on at least one surface of a separator main body to prevent diffusion of lithium polysulfide and improve the capacity and lifetime of the battery, Thereby providing a separation membrane. At least one surface of the separator main body is one surface or both surfaces necessarily including a surface facing the anode when assembling the electrode.
또한 니트록실 라디칼 관능기를 가지는 라디칼 화합물은 분리막 표면 또는 내부에 모두 위치할 수 있으며, 리튬-황 전지의 양극에서 생성되는 리튬 폴리설파이드의 확산을 방지하기 위해 바람직하게는 양극과 대향하는 분리막 표면에 위치할 수 있다.The radical compound having a nitroxyl radical functional group may be located on the surface or in the interior of the separation membrane and is preferably positioned on the surface of the separation membrane facing the anode in order to prevent the diffusion of lithium polysulfide produced in the anode of the lithium- can do.
도 1은 본 발명에 따른 리튬-황 전지를 보여주는 단면도이다. 도 1에 도시된 바와 같이, 리튬-황 전지는 양극(200), 음극(300)을 구비하고, 이들 사이에 전해질(400) 및 분리막(100)이 개재된 구조를 가지며, 특히, 본 발명은 분리막 본체(110)와 흡착층(120)이 순차적으로 적층된 분리막(100)을 제공한다. 이때 흡착층(120)은 도 1에 나타낸 바와 같이, 분리막 본체(110)의 일측 면에 형성될 수 있으며, 필요한 경우 양측 면에 형성이 가능하다.1 is a cross-sectional view showing a lithium-sulfur battery according to the present invention. 1, the lithium-sulfur battery includes a cathode 200 and a cathode 300, and an electrolyte 400 and a separator 100 interposed therebetween. In particular, And a separation membrane 100 in which a separation membrane body 110 and an adsorption layer 120 are sequentially laminated. At this time, as shown in FIG. 1, the adsorption layer 120 may be formed on one side of the separation membrane body 110, and may be formed on both sides if necessary.
상기 분리막 본체(110)는 본 발명에서 특별히 그 재질을 한정하지 않으며, 전극을 물리적으로 분리하고, 전해질 및 이온 투과능을 갖는 것으로서, 통상의 분리막으로 사용되는 것이라면 특별한 제한 없이 사용 가능하나, 다공성이고 비전도성 또는 절연성인 물질로서, 특히 전해액의 이온 이동에 대하여 저저항이면서 전해액 함습 능력이 우수한 것이 바람직하다.The separator main body 110 is not particularly limited in the present invention, and can be used without any particular limitation as long as it is physically separated from the electrode, has an electrolyte and ion permeability, and is used as a conventional separator. However, As the nonconductive or insulating material, it is preferable that the material has low resistance to ion movement of the electrolytic solution and excellent electrolytic solution impregnation ability.
구체적으로는 상기 분리막 본체(110)로는, 다공성 고분자 필름, 예를 들어 에틸렌 단독중합체, 프로필렌 단독중합체, 에틸렌/부텐 공중합체, 에틸렌/헥센 공중합체 및 에틸렌/메타크릴레이트 공중합체 등과 같은 폴리올레핀계 고분자로 제조한 다공성 고분자 필름을 단독으로 또는 이들을 적층하여 사용할 수 있으며, 또는 통상적인 다공성 부직포, 예를 들어 고융점의 유리 섬유, 폴리에틸렌테레프탈레이트 섬유 등으로 된 부직포를 사용할 수 있으나, 이에 한정되는 것은 아니다.Specifically, as the separator main body 110, a porous polymer film such as a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer and an ethylene / methacrylate copolymer Or a nonwoven fabric made of conventional porous nonwoven fabric such as high melting point glass fiber or polyethylene terephthalate fiber can be used, but the present invention is not limited thereto .
상기 흡착층(120)에 포함되는 니트록실 라디칼 관능기를 가지는 라디칼 화합물은 하기 화학식 1의 관능기를 가지는 구조를 의미한다.The radical compound having a nitroxyl radical functional group contained in the adsorption layer 120 means a structure having a functional group represented by the following formula (1).
Figure PCTKR2018005189-appb-C000001
Figure PCTKR2018005189-appb-C000001
상기 화학식 1에서 R1 및 R2는 각각 지방족, 방향족, 하이드록시기, 알콕시기, 알데하이드기, 카르복실기, 아미노기 또는 이들의 조합일 수 있고, 인접하는 것이 서로 결합해서 환을 형성할 수 있으며, 상기 R1 및 R2는 다르거나 동일할 수 있다.In Formula 1, R 1 and R 2 may be aliphatic, aromatic, hydroxyl, alkoxy, aldehyde, carboxyl, amino, or a combination thereof, R 1 and R 2 may be different or the same.
또한 본 발명에서 제공하는 라디칼 화합물은 분자 내 니트록실 라디칼 관능기를 가지는 폴리머일 수 있다.Also, the radical compound provided in the present invention may be a polymer having an intramolecular nitrosyl radical functional group.
이때, 폴리머는 (메타)아크릴레이트, 아크릴로나이트릴, 무수물, 스타이렌, 에폭시, 아이소시아네이트 및 비닐기로 구성된 군으로부터 선택된 어느 하나의 관능기를 포함하는 단량체로부터 중합된 것 일 수 있다.At this time, the polymer may be polymerized from a monomer containing any one functional group selected from the group consisting of (meth) acrylate, acrylonitrile, anhydride, styrene, epoxy, isocyanate and vinyl groups.
상기 폴리머는 폴리(2,2,6,6-테트라메틸-1-피페리디닐록시-4-일 메타아크릴레이트(PTMA), 폴리(2,2,6,6- 테트라메틸-1-피페리디닐록시-4-일 비닐에스터(PTVE), 폴리(TEMPO-치환 노보레인)(PTN), 폴리(2,2,5,5-테트라메틸피롤리딘-1-옥실-3-일 에틸렌 옥사이드(PTEO), 폴리[2,3-비스(2,2,6,6-테트라메틸피페리딘-1-옥실-4-옥시파보닐)-5-노보렌](PTNB), 폴리(테트라메틸피페리디녹시)아크릴아미드(PTAm) 및 이들의 조합으로 이루어진 군에서 선택된 1종 이상일 수 있다. 이때, 상기 TEMPO는 (2,2,6,6-테트라메틸피페리딘-1-일)옥실 화합물을 의미한다.The polymer may be selected from the group consisting of poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-ylmethacrylate (PTMA), poly (2,2,6,6-tetramethyl- (PTVE), poly (TEMPO-substituted norbornene) (PTN), poly (2,2,5,5-tetramethylpyrrolidine-1-oxyl-3-yl ethylene oxide PTEB), poly (2,3-bis (2,2,6,6-tetramethylpiperidine-1-oxyl-4-oxyphenyl) -5- (PTAm), and combinations thereof. The TEMPO may be at least one selected from the group consisting of (2,2,6,6-tetramethylpiperidin-1-yl) oxyl compound .
또한 상기 니트록실 라디칼 관능기를 가지는 라디칼 화합물은 폴리머로써 그 자체로도 흡착층을 형성할 수 있기 때문에, 본 발명에서 니트록실 라디칼 관능기를 가지는 라디칼 화합물의 함량은 흡착층 총 중량의 80 중량% 이상일 수 있다. Since the radical compound having a nitroxyl radical functional group can form an adsorption layer by itself as a polymer, the content of the radical compound having a nitroxyl radical functional group in the present invention may be 80 wt% or more of the total weight of the adsorbent layer have.
하기 화학식 2는 본 발명에서 제공하는 분자 내 니트록실 라디칼 관능기를 포함하고 중합반응에 의해 형성된 폴리머의 일종인 PTMA를 나타낸다.The following formula (2) represents PTMA which is a kind of polymer formed by the polymerization reaction, which contains the nitroxyl radical functional group in the molecule provided by the present invention.
Figure PCTKR2018005189-appb-C000002
Figure PCTKR2018005189-appb-C000002
상기 PTMA의 단량체 형태는 TEMPO(2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) 화합물로서, 폴리머 백본(backbone)에 부착되어 PTMA를 형성할 수 있다. The monomer type of the PTMA is TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl) oxyl) compound, which can be attached to a polymer backbone to form PTMA.
본 발명에서 제시하는 라디칼 화합물인 PTMA는 질소에서 산소로 전자의 비편재화 현상에 의해 비교적 안정한 화합물로 하기의 화학식 3을 통하여 PTMA의 안정성을 설명할 수 있다.PTMA which is a radical compound proposed in the present invention can explain the stability of PTMA through the following formula (3) as a relatively stable compound by the phenomenon of dissociation of electrons from nitrogen to oxygen.
Figure PCTKR2018005189-appb-C000003
Figure PCTKR2018005189-appb-C000003
상기 화학식 3을 살펴보면, (B) 상태에서 전자를 빼앗긴 PTMA는 (C) 상태의 활성화된 양이온(activated cation)으로 변하게 되고, (C) 상태에서의 PTMA가 하기 화학식 4와 같이 폴리설파이드(하기 화학식 4에서
Figure PCTKR2018005189-appb-I000001
)를 흡착하는 기능을 하게 된다.
The PTMA in the state (B) is changed into the activated cation in the state (C), and the PTMA in the state (C) is changed to the polysulfide In 4
Figure PCTKR2018005189-appb-I000001
As shown in FIG.
Figure PCTKR2018005189-appb-C000004
Figure PCTKR2018005189-appb-C000004
또한 본 발명에서는 고분자인 PTMA를 사용하는데, 이러한 PTMA는 분자량이 높기 때문에 전해액에 용해지 않고 분리막에 코팅시켜 사용할 수 있는 장점이 있다.In the present invention, PTMA which is a polymer is used. Since PTMA has a high molecular weight, it is advantageous that it can be coated on a separator without being dissolved in an electrolyte.
또한 본 발명의 흡착층(120)은 리튬-황 전지에 추가적인 전기 전도성을 부여하기 위하여, 상술한 니트록실 라디칼 관능기를 가지는 라디칼 화합물과 함께 전도성 물질을 포함할 수 있다. 리튬-황 전지의 양극 활물질인 황은 그 자체만으로는 전도성을 지니지 않기 때문에 도전성 탄소계 물질과 복합화하여 황-탄소 복합체의 양극(200)으로 제조하는 것이 일반적이다. 본 발명의 흡착층(120)은 전도성 물질을 포함하여, 양극 반응 사이트 이외에도 추가적인 황 물질의 환원 반응 사이트를 제공할 수 있다.In addition, the adsorption layer 120 of the present invention may include a conductive material together with the above-described radical compound having a nitrosyl radical functional group in order to impart additional electrical conductivity to the lithium-sulfur battery. Since sulfur, which is a positive electrode active material of a lithium-sulfur battery, does not have conductivity by itself, it is generally made of a composite of a conductive carbon material and an anode 200 of a sulfur-carbon composite. The adsorption layer 120 of the present invention may include a conductive material to provide additional sulfur reduction sites in addition to the anode reaction sites.
보다 구체적으로는 흡착층(120)은 전도성 물질의 다공성 구조로 인하여, 황의 환원 단계의 중간 생성물인 리튬 폴리설파이드(Lithium polysulfide, Li2Sx, x = 8, 6, 4, 2)(20)를 흡착하여 확산을 억제할 수 있다. 또한 흡착층(120)의 도전성 물질이 상기 흡착된 리튬 폴리설파이드(20)의 환원 반응 사이트를 추가적으로 제공하여 전극 효율을 높일 수 있다.More specifically, due to the porous structure of the conductive material, the adsorption layer 120 is formed of lithium polysulfide (Li 2 S x , x = 8, 6, 4, 2) 20, which is an intermediate product of the reduction step of sulfur, The diffusion can be suppressed. Further, the conductive material of the adsorption layer 120 may additionally provide a reduction reaction site of the adsorbed lithium polysulfide 20 to increase the electrode efficiency.
본 발명에 따른 흡착층(120)에 포함되는 상기 전도성 물질은 탄소계 도전재, 전도성 고분자 및 이들의 조합으로 이루어진 군으로부터 선택하는 것일 수 있다.The conductive material included in the adsorption layer 120 according to the present invention may be selected from the group consisting of a carbon-based conductive material, a conductive polymer, and a combination thereof.
상기 탄소계 도전재는 그 종류의 제한은 없으나, 천연 흑연, 인조 흑연, 팽창 흑연, 그래핀(Graphene), 슈퍼-피(Super-P), 슈퍼-씨(Super-C)와 같은 흑연(Graphite)계, 활성탄(Active carbon)계, 채널 블랙(Channel black), 덴카 블랙(Denka black), 퍼니스 블랙(Furnace black), 써말 블랙(Thermal black), 컨택트 블랙(Contact black), 램프 블랙(Lamp black), 아세틸렌 블랙(Acetylene black)과 같은 카본 블랙(Carbon black)계; 탄소 섬유(Carbon fiber)계, 탄소나노튜브(Carbon nanotube: CNT), 풀러렌(Fullerene)과 같은 탄소나노구조체 및 이들의 조합으로 이루어진 군으로부터 선택된 1종을 포함할 수 있으며, 바람직하게는 슈퍼-피를 사용할 수 있다.The carbon-based conductive material is not limited in its kind but may be graphite such as natural graphite, artificial graphite, expanded graphite, Graphene, Super-P and Super-C. Active black carbon black, Channel black, Denka black, Furnace black, Thermal black, Contact black, Lamp black, Carbon black such as acetylene black; Carbon nanotubes such as a carbon fiber, a carbon nanotube (CNT), and a fullerene, and combinations thereof. Preferably, the carbon nanotube may include a super- Can be used.
상기 전도성 고분자는 그 종류의 제한은 없으나, 폴리아닐린(Polyaniline), 폴리피롤(Polypyrrole), 폴리티오펜(Polythiopene), 폴라아줄렌(Polyazulene), 폴리피리딘(Polypyridine), 폴리인돌(Polyindole), 폴리카바졸(Polycarbazole), 폴리아진(Polyazine), 폴리퀴논(Polyquinone), 폴리아세틸렌(Polyacetylene), 폴리셀레노펜(Polyselenophene), 폴리텔루로펜(Polytellurophene), 폴리파라페닐렌(Poly-p-phenylene), 폴리페닐렌비닐렌(Polyphenylene vinylene), 폴리페닐렌설파이드(Polyphenylene sulfide), 폴리에틸렌디옥시티오펜(Polyethylenedioxythiophene), 폴리에틸렌글리콜(Polyethylene glycol) 및 이들의 조합으로 이루어진 군에서 선택된 1종을 포함하는 것일 수 있다.The conductive polymer may be selected from the group consisting of polyaniline, polypyrrole, polythiophene, polyazulene, polypyridine, polyindole, polycarbazole, Polycarbazole, Polyazine, Polyquinone, Polyacetylene, Polyselenophene, Polytellurophene, Poly-p-phenylene, Poly And may include one selected from the group consisting of polyphenylene vinylene, polyphenylene sulfide, polyethylene dioxythiophene, polyethylene glycol, and combinations thereof.
상술한 리튬 폴리설파이드 확산 방지 효과와 리튬 폴리설파이드의 환원 반응 사이트를 제공하기 위한 전도성 부여 효과를 위하여 니트록실 라디칼 관능기를 가지는 라디칼 화합물과 전도성 물질의 중량비는 3 : 1 ~ 7 : 1 범위 내에서 조절 가능하다. 만약, 상기한 범위보다 니트록실 라디칼 관능기를 가지는 라디칼 화합물을 과량 사용할 경우에는 저항층으로 작용하여 전지 성능 저하의 문제가 발생하고, 반대로 전도성 물질을 과량 사용할 경우에는 상대적으로 니트록실 라디칼 관능기를 가지는 라디칼 화합물의 함량이 감소되기 때문에 라디칼 화합물로 인한 효과를 확보하기 어려운 문제가 발생하므로, 상기 범위에서 적절히 사용하는 것이 바람직하다.The weight ratio of the radical compound having a nitrosyl radical functional group and the conductive material is controlled within a range of 3: 1 to 7: 1 for the above-described lithium polysulfide diffusion preventing effect and the conductivity imparting effect for providing the lithium polysulfide reduction reaction site It is possible. If an excess amount of a radical compound having a nitrosyl radical functional group is used in excess of the above-mentioned range, it acts as a resistive layer to deteriorate battery performance. On the contrary, when an excess amount of conductive material is used, a radical having a nitrosyl radical functional group It is difficult to secure the effect due to the radical compound because the content of the compound is decreased. Therefore, it is preferable to appropriately use the compound in the above range.
이러한 흡착층(120)은 상기한 효과를 확보하기 위해 분리막 본체(110) 상에 0.1 ~ 10㎛, 바람직하게는 0.1 ~ 5㎛의 두께로 형성할 수 있다. 만약 그 두께가 상기 범위 미만이면 리튬 폴리설파이드 흡착 효과가 미비하고, 이와 반대로 상기 범위를 초과할 경우에는 리튬 이온 전도성이 저하되어 전극 성능에 문제가 발생하므로, 상기 범위 내에서 적절히 사용하는 것이 바람직하다.The adsorption layer 120 may be formed on the separation membrane body 110 to have a thickness of 0.1 to 10 탆, preferably 0.1 to 5 탆, in order to secure the above-mentioned effect. If the thickness is less than the above range, the effect of adsorbing lithium polysulfide is insufficient. On the other hand, if the thickness exceeds the above range, the lithium ion conductivity is lowered to cause problems in electrode performance. Therefore, .
또한 본 발명 황-탄소 복합체를 포함하는 양극; 상기 양극과 대향 배치되는 음극; 및 상기 양극과 음극 사이에 개재되는 분리막을 포함하는 리튬-황 전지로서, 상기 분리막의 일부에 테트라메틸 피페리딘 N-옥실을 포함하는 리튬-황 전지를 제공한다. 이때, 분리막에 포함된 테트라메틸 피페리딘 N-옥실은 전지의 방전 및 충전 동안 전해질에 용해될 수 있다.A cathode comprising the sulfur-carbon composite of the present invention; A cathode arranged opposite to the anode; And a separator interposed between the anode and the cathode. The lithium-sulfur battery includes tetramethylpiperidine N-oxyl in a part of the separator. At this time, the tetramethylpiperidine N-oxyl contained in the separator may be dissolved in the electrolyte during discharging and charging of the battery.
리튬-황 전지용 분리막 제조방법Manufacturing method of separator for lithium-sulfur battery
본 발명에 따른 리튬-황 전지의 분리막은 i) 분리막 본체를 준비하는 단계; ii) 니트록실 라디칼 부위를 가지는 라디칼 화합물을 용매에 혼합하여 용액을 제조하는 단계; iii) 상기 용액을 분리막 본체의 적어도 일면에 코팅하는 단계; 및 iv) 상기 코팅된 분리막을 건조하여 리튬 폴리설파이드 흡착층을 형성하는 단계를 포함하는 것을 특징으로 제조될 수 있다.The separation membrane of the lithium-sulfur battery according to the present invention comprises i) preparing a separator main body; ii) preparing a solution by mixing a radical compound having a nitroxyl radical portion in a solvent; iii) coating the solution on at least one side of the membrane body; And iv) drying the coated separator to form a lithium polysulfide adsorption layer.
먼저, 분리막 본체(110)를 준비한다. 분리막 본체(110)는 본 발명에서 특별히 한정하지 않으며, 전술한 분리막 본체 중 어느 하나를 선택할 수 있고, 직접 제조하거나 시판되는 분리막을 구입하여 사용하는 것이 가능하다.First, the separator main body 110 is prepared. The separation membrane body 110 is not particularly limited in the present invention, and any one of the separation membrane bodies described above can be selected, and it is possible to purchase or use a commercially available separation membrane.
다음으로, 니트록실 라디칼 관능기를 가지는 라디칼 화합물을 소정의 용매에 분산시켜 라디칼 화합물 용액을 제조한다. 상기 용매로는 라디칼 화합물을 균일하게 분산시킬 수 있고, 쉽게 증발되어 건조가 용이한 것을 사용하는 것이 바람직하며, 구체적으로는 N-메틸-2-피롤리돈(NMP), 아세토니트릴, 메탄올, 에탄올, 테트라하이드로퓨란, 물, 이소프로필알코올 등을 들 수 있으며, 바람직하게는 NMP를 사용할 수 있다. 또한 상기 라디칼 화합물 용액 제조를 위한 혼합은 통상의 혼합기, 예컨대 페이스트 믹서, 고속 전단 믹서, 호모 믹서 등을 이용하여 통상의 방법으로 교반할 수 있다.Next, a radical compound having a nitrosyl radical functional group is dispersed in a predetermined solvent to prepare a radical compound solution. As the solvent, it is preferable to use a solvent which can uniformly disperse the radical compound and is easily evaporated and can be dried. Specifically, N-methyl-2-pyrrolidone (NMP), acetonitrile, methanol, ethanol , Tetrahydrofuran, water, isopropyl alcohol, and the like, and preferably NMP can be used. The mixing for the preparation of the radical compound solution may be carried out by a conventional method using a conventional mixer such as a paste mixer, a high-speed shear mixer, a homomixer or the like.
다음으로, 상기 제조된 용액을 분리막 본체(110)의 일면에 코팅한다. 여기에서 분리막 본체(110)의 일면이란, 추후 전극 조립시, 양극(200)과 대향하여 조립되는 분리막 본체(110)의 일면이다. 이때 상기 슬러리를 코팅하는 방법으로 예컨대, 닥터 블레이드 코팅(Doctor blade coating), 딥 코팅(Dip coating), 그라비어 코팅(Gravure coating), 슬릿 다이 코팅(Slit die coating), 스핀 코팅(Spin coating), 콤마 코팅(Comma coating), 바 코팅(Bar coating), 리버스 롤 코팅(Reverse roll coating), 스크린 코팅(Screen coating), 캡 코팅(Cap coating) 방법 등을 수행하여 제조할 수 있다.Next, the prepared solution is coated on one surface of the separator main body 110. Here, one surface of the separator main body 110 is one surface of the separator main body 110 which is assembled opposite to the anode 200 at the time of later electrode assembly. At this time, as a method of coating the slurry, for example, a doctor blade coating, a dip coating, a gravure coating, a slit die coating, a spin coating, a comma A reverse coating method, a screen coating method, a cap coating method, and the like, may be used.
다음으로, 상기 코팅된 분리막을 건조하여 흡착층(120)을 형성한다. 상기 건조 공정은, 분리막에 코팅된 흡착층(120) 내의 용매 및 수분을 제거하는 과정으로, 사용한 용매에 따라 건조 온도 및 시간이 달라질 수 있으며, 일반적으로 50 ~ 200℃의 진공 오븐에서 48시간 이내로 건조하는 것이 바람직하다. Next, the coated separation membrane is dried to form an adsorption layer 120. The drying process is a process of removing the solvent and moisture in the adsorption layer 120 coated on the separation membrane. The drying temperature and time may vary depending on the solvent used. Generally, the drying process is performed in a vacuum oven at 50 to 200 ° C within 48 hours Drying is preferred.
또한 흡착층(120)은 본 발명에 따른 니트록실 라디칼 관능기를 가지는 라디칼 화합물이 폴리머로써 그 자체로도 흡착층을 형성할 수 있기 때문에, 상기 라디칼 화합물의 함량은 흡착층 총 중량의 80 중량% 이상일 수 있다.In addition, since the radical compound having a nitrosyl radical functional group according to the present invention can form an adsorption layer by itself as the polymer, the content of the radical compound is not less than 80% by weight of the total weight of the adsorption layer .
리튬-황 전지Lithium-sulfur battery
본 발명에서는, 황-탄소 복합체를 포함하는 양극; 상기 양극과 대향 배치되는 음극; 및 상기 양극과 음극 사이에 개재되는 분리막을 포함하는 리튬-황 전지로서, 상기 분리막은 분리막 본체; 및 상기 분리막 본체의 적어도 일면에 형성된 리튬 폴리설파이드 흡착층을 포함하고, 상기 흡착층은 니트록실 라디칼 관능기를 가지는 라디칼 화합물을 포함하는 것을 특징으로 하는 리튬-황 전지를 제공한다.In the present invention, a positive electrode comprising a sulfur-carbon composite; A cathode arranged opposite to the anode; And a separator interposed between the anode and the cathode, wherein the separator comprises a separator main body; And a lithium polysulfide adsorbent layer formed on at least one side of the separator main body, wherein the adsorbent layer comprises a radical compound having a nitrosyl radical functional group.
본 발명에서 제시하는 분리막(100)은 바람직하게 리튬-황 전지의 분리막으로 적용 가능하며, 도 1에 제시한 바와 같이, 분리막(100)은 양극(200) 및 음극(300) 사이에 개재되고, 이때 흡착층(120)이 일면에만 코팅되는 경우, 바람직하게는 리튬 폴리설파이드의 확산을 방지하기 위해 흡착층(120)이 양극(200)과 대향하도록 배치하여 조립하도록 한다.1, the separation membrane 100 may be interposed between the anode 200 and the cathode 300, and may be a separator of the lithium-sulfur battery, At this time, when the adsorption layer 120 is coated on only one surface, the adsorption layer 120 is preferably arranged to face the anode 200 in order to prevent diffusion of lithium polysulfide.
상기 양극(200)은 양극 활물질로서 황 원소(Elemental sulfur, S8), 황 계열 화합물 또는 이들의 혼합물을 포함할 수 있으며, 이들은 황 물질 단독으로는 전기 전도성이 없기 때문에 도전재와 복합하여 적용한다. 상기 황 계열 화합물은 구체적으로, Li2Sn(n≥1), 유기황 화합물 또는 탄소-황 폴리머((C2Sx)n: x=2.5 ~ 50, n≥2) 등일 수 있다.The anode 200 may include a sulfur element (S 8 ) as a cathode active material, a sulfur-based compound, or a mixture thereof. Since the sulfur element alone does not have electrical conductivity, the anode 200 may be used in combination with a conductive material . Specifically, the sulfur-based compound may be Li 2 S n ( n ? 1), an organic sulfur compound or a carbon-sulfur polymer ((C 2 S x ) n : x = 2.5 to 50, n?
리튬-황 전지의 양극으로 수명특성이 좋은 SPAN(sulfurized poly-acrylonitrile) 양극을 사용할 수 있으나, SPAN 양극의 경우 평균 작동 전압이 1.7V로, 평균 작동전압 2.1V의 황-탄소 복합체 양극에 비해 에너지 밀도가 낮으며, SPAN 양극의 경우 황의 함유량도 황-탄소 복합체 양극에 비해 40% 가까이 작기 때문에, 본 발명에서 리튬-황 전지의 양극은 황-탄소 복합체 양극으로 한정하기로 한다.A sulfurized poly-acrylonitrile (SPAN) anode with good lifetime characteristics can be used as the anode of the lithium-sulfur battery. However, the average operating voltage of the SPAN anode is 1.7 V and the energy Since the density is low and the content of sulfur in the SPAN anode is also about 40% smaller than that in the sulfur-carbon composite anode, the anode of the lithium-sulfur battery is limited to the anode of the sulfur-carbon composite.
상기 도전재는 다공성일 수 있다. 따라서, 상기 도전재로는 다공성 및 도전성을 갖는 것이라면 제한 없이 사용할 수 있으며, 예를 들어 다공성을 갖는 탄소계 물질을 사용할 수 있다. 이와 같은 탄소계 물질로는 카본 블랙, 그라파이트, 그래핀, 활성탄, 탄소 섬유, 탄소나노튜브(CNT) 등을 사용할 수 있다. 또한, 금속 메쉬 등의 금속성 섬유; 구리, 은, 니켈, 알루미늄 등의 금속성 분말; 또는 폴리페닐렌 유도체 등의 유기 도전성 재료도 사용할 수 있다. 상기 도전성 재료들은 단독 또는 혼합하여 사용할 수 있다. The conductive material may be porous. Therefore, any conductive material having porosity and conductivity may be used without limitation, and for example, a carbon-based material having porosity may be used. Examples of the carbon-based material include carbon black, graphite, graphene, activated carbon, carbon fiber, and carbon nanotube (CNT). Further, metallic fibers such as metal mesh; Metallic powder such as copper, silver, nickel, and aluminum; Or an organic conductive material such as a polyphenylene derivative can also be used. The conductive materials may be used alone or in combination.
상기 음극(300)은 음극 활물질로서 리튬 이온(Li+)을 가역적으로 흡장(Intercalation) 또는 방출(Deintercalation)할 수 있는 물질, 리튬 이온과 반응하여 가역적으로 리튬 함유 화합물을 형성할 수 있는 물질, 리튬 금속 또는 리튬 합금을 사용할 수 있다. 상기 리튬 이온(Li+)을 가역적으로 흡장 또는 방출할 수 있는 물질은 예컨대 결정질 탄소, 비정질 탄소 또는 이들의 혼합물일 수 있다. 상기 리튬 이온(Li+)과 반응하여 가역적으로 리튬 함유 화합물을 형성할 수 있는 물질은 예를 들어, 산화주석, 티타늄나이트레이트 또는 실리콘일 수 있다. 상기 리튬 합금은 예를 들어, 리튬(Li)과 나트륨(Na), 칼륨(K), 루비듐(Rb), 세슘(Cs), 프랑슘(Fr), 베릴륨(Be), 마그네슘(Mg), 칼슘(Ca), 스트론튬(Sr), 바륨(Ba), 라듐(Ra), 알루미늄(Al), 실리콘(Si) 및 주석(Sn)으로 이루어지는 군에서 선택되는 금속의 합금일 수 있다.The negative electrode 300 is a negative electrode active material that can reversibly intercalate or deintercalate lithium ions Li + , a material capable of reversibly reacting with lithium ions to form a lithium-containing compound, lithium A metal or a lithium alloy can be used. The material capable of reversibly storing or releasing lithium ions (Li < + & gt ; ) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The material capable of reacting with the lithium ion (Li < + & gt ; ) to reversibly form a lithium-containing compound may be, for example, tin oxide, titanium nitride or silicon. The lithium alloy includes, for example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg) Ca, Sr, Ba, Ra, Al, Si, and Sn. The metal may be an alloy of a metal selected from the group consisting of Ca, Sr, Ba,
또한, 리튬-황 전지를 충ㆍ방전하는 과정에서, 양극 활물질로 사용되는 황이 비활성 물질로 변화되어, 리튬 음극 표면에 부착될 수 있다. 이와 같이 비활성 황(Inactive sulfur)은 황이 여러 가지 전기화학적 또는 화학적 반응을 거쳐 양극의 전기화학 반응에 더 이상 참여할 수 없는 상태의 황을 의미하며, 리튬 음극 표면에 형성된 비활성 황은 리튬 음극의 보호막(Protective layer)으로서 역할을 하는 장점도 있다.In addition, in the course of charging / discharging the lithium-sulfur battery, sulfur used as a cathode active material is changed to an inactive material and can be attached to the surface of the lithium anode. Inactive sulfur is sulfur in which sulfur can not participate in the electrochemical reaction of the anode after various electrochemical or chemical reactions. Inactive sulfur formed on the surface of the lithium anode is a protective film of the lithium anode layer as well.
상기 양극(200), 음극(300) 및 분리막(100)에 함침되어 있는 전해질(400)은 리튬염을 함유하는 비수계 전해질로서 리튬염과 전해액으로 구성되어 있으며, 이외에도 유기 고체 전해질 및 무기 고체 전해질 등이 사용될 수 있다.The electrolyte 400 impregnated into the anode 200, the cathode 300 and the separator 100 is a non-aqueous electrolyte containing a lithium salt and is composed of a lithium salt and an electrolyte. In addition, the organic solid electrolyte and the inorganic solid electrolyte Etc. may be used.
본 발명의 리튬염은 비수계 유기용매에 용해되기 좋은 물질로서, 예컨대, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl10, LiB(Ph)4 , LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, LiSO3CH3, LiSO3CF3, LiSCN, LiC(CF3SO2)3, LiN(CF3SO2)2, LiNO3, 클로로 보란 리튬, 저급 지방족 카르본산 리튬, 4 페닐 붕산 리튬, 이미드로 이루어진 군으로부터 하나 이상이 포함될 수 있다.The lithium salt of the present invention can be dissolved in a non-aqueous organic solvent, for example, LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiB (Ph) 4 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, LiSO 3 CH 3, LiSO 3 CF 3, LiSCN, LiC (CF 3 SO 2) 3, LiN (CF 3 SO 2) 2, LiNO 3, chloroborane lithium , Lower aliphatic carboxylic acid lithium, lithium 4-phenylborate, and imide.
상기 리튬염의 농도는, 전해질 혼합물의 정확한 조성, 염의 용해도, 용해된 염의 전도성, 전지의 충전 및 방전 조건, 작업 온도 및 리튬 배터리 분야에 공지된 다른 요인과 같은 여러 요인에 따라, 0.2 ~ 4M, 구체적으로 0.3 ~ 2M, 더욱 구체적으로 0.3 ~ 1.5M일 수 있다. 0.2M 미만으로 사용하면 전해질의 전도도가 낮아져서 전해질 성능이 저하될 수 있고, 4M을 초과하여 사용하면 전해질의 점도가 증가하여 리튬 이온(Li+)의 이동성이 감소될 수 있다.The concentration of the lithium salt may be 0.2 to 4 M according to various factors such as the precise composition of the electrolyte mixture, the solubility of the salt, the conductivity of the dissolved salt, the charging and discharging conditions of the battery, the working temperature and other factors known to the lithium battery To 0.3 M, more specifically 0.3 M to 1.5 M, for example. If it is used at less than 0.2 M, the conductivity of the electrolyte may be lowered and electrolyte performance may be deteriorated. If it is used in excess of 4 M, the viscosity of the electrolyte may increase and the mobility of lithium ion (Li + ) may be decreased.
상기 비수계 유기용매는 리튬염을 잘 용해시켜야 하며, 본 발명의 비수계 유기용매로는, 예컨대, N-메틸-2-피롤리디논, 프로필렌 카보네이트, 에틸렌 카보네이트, 부틸렌 카보네이트, 디메틸 카보네이트, 디에틸 카보네이트, 에틸메틸 카보네이트, 감마-부틸로 락톤, 1,2-디메톡시 에탄, 1,2-디에톡시 에탄, 테트라히드록시 프랑(franc), 2-메틸 테트라하이드로푸란, 디메틸술폭시드, 1,3-디옥솔란, 4-메틸-1,3-디옥센, 디에틸에테르, 포름아미드, 디메틸포름아미드, 디옥솔란, 아세토니트릴, 니트로메탄, 포름산 메틸, 초산메틸, 인산 트리에스테르, 트리메톡시 메탄, 디옥솔란 유도체, 설포란, 메틸설포란, 1,3-디메틸-2-이미다졸리디논, 프로필렌 카보네이트 유도체, 테트라하이드로푸란 유도체, 에테르, 프로피온산 메틸, 프로피온산 에틸 등의 비양자성 유기용매가 사용될 수 있으며, 상기 유기 용매는 하나 또는 둘 이상의 유기 용매들의 혼합물일 수 있다.Examples of the non-aqueous organic solvent of the present invention include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, di Ethyl carbonate, ethyl methyl carbonate, gamma-butylolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, Diethyl ether, formamide, dimethyl formamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane , A dioxolane derivative, an aprotic organic solvent such as sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate or ethyl propionate And the organic solvent may be one or a mixture of two or more organic solvents.
상기 유기 고체 전해질로는, 예컨대, 폴리에틸렌 유도체, 폴리에틸렌 옥사이드 유도체, 폴리프로필렌 옥사이드 유도체, 인산 에스테르 폴리머, 폴리 에지테이션 리신(Agitation lysine), 폴리에스테르 설파이드, 폴리비닐 알코올, 폴리 불화 비닐리덴, 이온성 해리기를 포함하는 중합체 등이 사용될 수 있다.Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer including a group can be used.
본 발명의 무기 고체 전해질로는, 예컨대, Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, Li3PO4-Li2S-SiS2 등의 Li의 질화물, 할로겐화물, 황산염 등이 사용될 수 있다. Examples of the inorganic solid electrolyte of the present invention include Li 3 N, LiI, Li 5 NI 2 , Li 3 N-LiI-LiOH, LiSiO 4 , LiSiO 4 -LiI-LiOH, Li 2 SiS 3 , Li 4 SiO 4 , Nitrides, halides and sulfates of Li such as Li 4 SiO 4 -LiI-LiOH and Li 3 PO 4 -Li 2 S-SiS 2 can be used.
본 발명의 전해질에는 충ㆍ방전 특성, 난연성 등의 개선을 목적으로, 예컨대, 피리딘, 트리에틸포스파이트, 트리에탄올아민, 환상 에테르, 에틸렌 디아민, n-글라임(glyme), 헥사 인산 트리 아미드, 니트로벤젠 유도체, 유황, 퀴논 이민 염료, N-치환 옥사졸리디논, N,N-치환 이미다졸리딘, 에틸렌 글리콜 디알킬 에테르, 암모늄염, 피롤, 2-메톡시 에탄올, 삼염화 알루미늄 등이 첨가될 수도 있다. 경우에 따라서는, 불연성을 부여하기 위하여, 사염화탄소, 삼불화에틸렌 등의 할로겐 함유 용매를 더 포함시킬 수도 있고, 고온 보존 특성을 향상시키기 위하여 이산화탄산 가스를 더 포함시킬 수도 있으며, FEC(Fluoro-ethylene carbonate), PRS(Propene sultone), FPC(Fluoro-propylene carbonate) 등을 더 포함시킬 수 있다.The electrolyte of the present invention may be added to the electrolyte for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, hexaphosphoric triamide, Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, . In some cases, a halogen-containing solvent such as carbon tetrachloride, ethylene trifluoride or the like may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. carbonate, PRS (propene sultone), FPC (fluoro-propylene carbonate) and the like.
또한 본 발명에 따른 리튬-황 전지는 리튬-황 전지 분야에서 통상적으로 사용하는 첨가제를 포함할 수 있고, 바람직하게는 비닐렌 카보네이트(VC) 또는 에틸렌 카보네이트(EC)일 수 있다.Further, the lithium-sulfur battery according to the present invention may include additives commonly used in the lithium-sulfur battery field, and preferably, it may be vinylene carbonate (VC) or ethylene carbonate (EC).
상술한 양극(200)과 음극(300)을 소정의 크기로 절취한 양극판과 음극판 사이에 상기 양극판과 음극판에 대응하는 소정의 크기로 절취한 분리막(100)을 개재시킨 후 적층함으로써 스택형 전극 조립체를 제조할 수 있다.The separator 100 cut to a predetermined size corresponding to the positive electrode plate and the negative electrode plate is interposed between the positive electrode plate and the negative electrode plate obtained by cutting the positive electrode 200 and the negative electrode 300 to a predetermined size, Can be produced.
또한 양극(200)과 음극(300)이 분리막(100) 시트를 사이에 두고 대향하도록, 둘 이상의 양극판 및 음극판들을 분리막 시트 상에 배열하거나 또는 상기 둘 이상의 양극판 및 음극판들이 분리막을 사이에 두고 적층되어 있는 유닛셀들 둘 이상을 분리막 시트 상에 배열하고, 상기 분리막 시트를 권취하거나, 전극판 또는 유닛셀의 크기로 분리막 시트를 절곡함으로써 스택 앤 폴딩형 전극 조립체를 제조할 수 있다.Also, two or more positive plates and negative plates may be arranged on the separator sheet so that the positive electrode 200 and the negative electrode 300 face each other with the separator 100 sheet therebetween, or the two or more positive and negative plates may be stacked with the separator interposed therebetween Stacked and folded electrode assemblies can be manufactured by arranging two or more unit cells on the separator sheet, winding the separator sheet, or bending the separator sheet to the size of the electrode plate or unit cell.
상기한 리튬-황 전지를 포함하는 전지팩은 전기자동차(Electric Vehicle, EV), 하이브리드 전기자동차(Hybrid Electric Vehicle, HEV), 플러그-인 하이브리드 전기자동차(Plug-in Hybrid Electric Vehicle, PHEV), 전력 저장장치의 전원으로 사용될 수 있다.The battery pack including the lithium-sulfur battery includes an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV) And can be used as a power source of a storage device.
이하, 본 발명을 구체적으로 설명하기 위해 실시예를 들어 상세하게 설명하기로 한다. 그러나 본 발명에 따른 실시예는 여러 가지 다른 형태로 변형될 수 있으며, 본 발명의 범위가 아래에서 상술하는 실시예에 한정되는 것으로 해석되어서는 안 된다. 본 발명의 실시예는 당업계에서 평균적인 지식을 가진 자에게 본 발명을 보다 완전하게 설명하기 위해서 제공되는 것이다.BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.
실시예Example
제조예. 분리막 제조Production example. Membrane manufacturing
PTMA를 N-메틸-2-피롤리돈(NMP)에 녹여 PTMA 1wt% 용액을 제조하였다. PTMA was dissolved in N-methyl-2-pyrrolidone (NMP) to prepare a 1 wt% PTMA solution.
20㎛ 두께의 폴리 프로필렌 분리막 위에 상기 용액을 바코터를 이용하여 도포한 후, 진공 건조 과정을 거쳐 0.5 ㎛의 PTMA가 코팅된 분리막을 제조하였다.The solution was coated on a polypropylene separator having a thickness of 20 μm using a bar coater, followed by vacuum drying to prepare a 0.5 μm PTMA-coated separator.
실시예 1. 리튬-황 전지 제조Example 1 Preparation of lithium-sulfur battery
탄소 및 황을 9 : 1의 중량비로 혼합하여 제조된 양극 활물질 70 중량%, 도전재인 Denka black 20 중량% 및 바인더로서 SBR/CMC(중량비 1 : 1) 10 중량% 조성의 양극 합제를 D.I water에 첨가하여 양극 슬러리를 제조한 후, 알루미늄 집전체에 코팅하여 양극을 제조하였다. 단, 바인더에서 SBR은 스티렌 부타디엔 고무이고, CMC는 카복시메틸셀룰로오스이다.A positive electrode mixture of 70 wt% of a cathode active material prepared by mixing carbon and sulfur at a weight ratio of 9: 1, 20 wt% of Denka black as a conductive material, and 10 wt% of SBR / CMC as a binder (weight ratio 1: 1) To prepare a positive electrode slurry, and then coated on an aluminum current collector to prepare a positive electrode. In the binder, SBR is styrene butadiene rubber, and CMC is carboxymethyl cellulose.
음극으로서 150㎛ 두께를 갖는 리튬 호일을 사용하였다. 상기 제조예에서 제조된 분리막에 1M LiN(CF3SO2)2가 용해된 디메톡시에탄과 디옥솔란을 1 : 1의 부피비로 혼합한 전해액을 70㎕ 개재하고, 상기 양극과 음극 사이에 상기 분리막을 개재하여 전극 조립체를 제조하였다. 상기 전극 조립체를 전지케이스에 수납하여 리튬-황 전지 코인셀을 제조하였다.Lithium foil having a thickness of 150 mu m was used as a cathode. 70 쨉 l of an electrolytic solution obtained by mixing 1M LiN (CF 3 SO 2 ) 2 dissolved in dimethoxyethane and dioxolane in a volume ratio of 1: 1 was introduced into the separator prepared in the above Preparation Example, To produce an electrode assembly. The electrode assembly was housed in a battery case to prepare a lithium-sulfur battery coin cell.
비교예Comparative Example
비교 제조예. PTMA를 함유하지 않은 분리막 제조Comparative Production Example. Preparation of PTMA-free membrane
상기 폴리프로필렌에 PTMA 용액이 코팅된 분리막 대신에, PTMA 용액이 코팅되지 않은 20㎛ 두께의 폴리프로필렌 필름을 분리막으로 사용하는 것을 제외하고는 상기 제조예와 동일한 방법으로 분리막을 제조하였다.A separator was prepared in the same manner as in the above preparation example, except that a polypropylene film having a thickness of 20 탆 in which no PTMA solution was coated was used as a separator instead of the separator in which the PTFE solution was coated on the polypropylene.
비교예 1. 리튬-황 전지 제조Comparative Example 1. Preparation of lithium-sulfur battery
실시예 1에서 상기 폴리프로필렌에 PTMA 용액이 코팅된 분리막 대신에, 비교 제조예 1의 분리막을 사용하는 것을 제외하고는 실시예 1과 동일한 방법으로 코인셀을 제작하였다.A coin cell was fabricated in the same manner as in Example 1, except that the separation membrane of Comparative Production Example 1 was used instead of the separation membrane in which the PTMA solution was coated on the polypropylene in Example 1.
비교예 2. 리튬-황 전지 제조Comparative Example 2. Preparation of lithium-sulfur battery
PTMA를 분리막에 코팅하지 않고, 탄소 및 황을 9 : 1의 중량비로 혼합하여 제조된 양극 활물질 70 중량%, 도전재인 Denka black 20 중량% 및 바인더로서 SBR/CMC(중량비 1 : 1) 9 중량% 및 PTMA 1중량% 조성의 양극 합제를 D.I water에 첨가하여 양극 슬러리를 제조한 후, 알루미늄 집전체에 코팅하여 양극을 제조한 것을 제외하고는 실시예 1과 동일한 방법으로 리튬-황 전지 코인셀을 제조하였다.PTMA was not coated on the separator but mixed with 70 wt% of a cathode active material prepared by mixing carbon and sulfur at a weight ratio of 9: 1, 20 wt% of Denka black as a conductive material and 9 wt% of SBR / CMC (weight ratio of 1: 1) And 1% by weight of PTMA were added to DI water to prepare a positive electrode slurry and then coated on an aluminum current collector to prepare a positive electrode. A lithium-sulfur battery coin cell was prepared in the same manner as in Example 1, .
비교예 3. 리튬-황 전지 제조Comparative Example 3. Preparation of lithium-sulfur battery
상기 실시예 1에서 PTMA가 코팅된 폴리프로필렌 분리막 대신에, PTMA 용액에 분리막을 1분간 담지하여 분리막 내부까지 PTMA가 함침된 분리막을 사용한 것을 제외하고는 실시예 1과 동일한 방법으로 리튬-황 전지 코인셀을 제조하였다.In the same manner as in Example 1, except that the PTFE-coated polypropylene separator membrane in Example 1 was used, and a separator membrane impregnated with PTMA to the interior of the separator membrane was carried by PTMA solution for 1 minute, Cells were prepared.
분리막 표면 분석 결과Membrane surface analysis results
제조예와 비교 제조예의 분리막 표면을 주사전자현미경(SEM)을 통해 확인하였다. The separation membrane surfaces of the preparation examples and comparative preparation examples were confirmed by scanning electron microscopy (SEM).
제조예에 따른 분리막의 표면(도 2)을 확인한 결과, 비교 제조예에 따른 분리막의 표면(도 3)과 비교하여 코팅 전 후 표면상의 큰 변화가 보이지 않았으므로, PTMA 용액이 분리막에 얇고 균일하게 코팅된 것을 확인하였다.As a result of checking the surface of the separation membrane according to the production example (FIG. 2), no significant change was seen on the surface before and after coating as compared with the surface of the separation membrane according to the comparative preparation example (FIG. 3) Coating.
저항 측정 결과Resistance measurement result
실시예 1과 비교예 1에 의해 동일한 코인셀을 각각 3개씩 제조하여 각 시료의 저항을 측정하였다.Three coin cells were produced in the same manner as in Example 1 and Comparative Example 1, and the resistance of each sample was measured.
각 시료들의 저항 측정 값의 평균과 표준편차를 하기 표 1에 나타내었다.The mean and standard deviation of the resistance measurements of each sample are shown in Table 1 below.
샘플명Sample name 측정된 저항값(ohm)Measured resistance value (ohm)
비교예 1Comparative Example 1 1.3 ± 0.41.3 ± 0.4
실시예 1Example 1 1.4 ± 0.41.4 ± 0.4
각 3개씩의 시료의 저항값을 측정하여 평균 및 표준편차를 확인한 결과, PTMA 용액이 코팅된 분리막이 적용된 전지의 저항 증가가 비교예 1에 비해 미미하였다. 따라서 코팅 후의 저항 증가로 인한 전지의 성능 저하는 거의 없음을 확인하였다.The resistance value of each sample was measured and the average and standard deviation were checked. As a result, the resistance increase of the battery using the PTMA solution-coated separator was less than that of Comparative Example 1. [ Therefore, it was confirmed that the performance of the battery was not substantially deteriorated due to the increase in resistance after coating.
리튬-황 전지 수명 특성 시험Lithium-sulfur battery life characteristic test
상기 실시예 1 및 비교예 1 내지 3의 전지의 수명 특성을 비교하기 위하여, 다음 조건에서 충방전을 반복하며 비 방전 용량(Specific discharging capacity) 및 쿨롱 효율(Coulombic Efficiency)을 측정하였다.In order to compare lifetime characteristics of the batteries of Example 1 and Comparative Examples 1 to 3, specific discharging capacity and coulombic efficiency were measured by repeating charging and discharging under the following conditions.
충전: 전압 2.6V 종료조건, CC/CV (5% current cut at 0.1C)Charging: voltage 2.6V termination condition, CC / CV (5% current cut at 0.1C)
방전: 전압 1.8V 종료조건, CCDischarge: Voltage 1.8V Termination condition, CC
충/방전 모두 초기 3 cycle 동안 율속 0.1C, 이후 3 cycle 율속 0.2C, 이후 0.5C로 평가 (매 10사이클에 3번 0.2C로 평가)The rate of charge / discharge was evaluated at 0.1C for the initial 3 cycles, then at 0.2C for 3 cycles and then at 0.5C (evaluated at 0.2C for 3 cycles every 10 cycles)
실시예 1 및 비교예 1의 전지의 비 방전 용량 및 쿨롱 효율을 각각 도 4에 나타내었다.The non-discharge capacity and the coulombic efficiency of the batteries of Example 1 and Comparative Example 1 are shown in Fig. 4, respectively.
도 4를 참조하면, PTMA가 코팅된 분리막을 이용한 리튬-황 전지인 실시예 1의 경우 비교예 1에 비하여 현저히 개선된 용량 유지율 및 쿨롱 효율을 나타내는 것을 알 수 있다.Referring to FIG. 4, it can be seen that Example 1, which is a lithium-sulfur battery using a PTMA-coated separator, exhibits remarkably improved capacity retention and coulon efficiency as compared with Comparative Example 1.
도 8을 보면 PTMA를 분리막에 코팅하지 않고, 리튬-황 전지의 바인더로 적용한 비교예 2의 경우, 실시예 1에 비해 전지의 용량 유지율 및 쿨롱 효율이 저하되는 것을 알 수 있었다. 8 shows that the capacity retention rate and the coulombic efficiency of the battery of Comparative Example 2, in which the PTMA is not coated on the separator but applied to the binder of the lithium-sulfur battery, are lower than those of Example 1.
또한 PTMA를 분리막에 함침시킨 비교예 3의 경우, 분리막의 기공을 막아 리튬 이온 전도도가 떨어지므로, 역시 실시예 1에 비해 전지의 용량 유지율 및 쿨롱 효율이 저하되는 것을 도 9를 통해 알 수 있었다.In the case of Comparative Example 3 in which the PTMA was impregnated into the separator, the capacity retention rate and the coulomb efficiency of the battery were lowered as compared with Example 1 because the lithium ion conductivity was lowered by blocking the pores of the separator.
리튬-황 전지 방전 사이클 특성 시험Lithium-sulfur battery discharge cycle characteristics test
상기 실시예 1 및 비교예 1의 전지의 방전 특성을 비교하기 위하여, 충방전 사이클에 따른 방전 용량을 측정하였다.In order to compare the discharge characteristics of the batteries of Example 1 and Comparative Example 1, the discharge capacity according to charge / discharge cycles was measured.
도 5 내지 도 7을 비교해보면, 실시예 1의 리튬-황 전지가 PTMA에 의한 폴리설파이드의 흡착 효과로 인하여, 10 사이클 후, 30 사이클 및 60 사이클 후에도 비교예 1보다 우수한 890 mAh/g 수준의 용량을 보이는 것으로 나타났다.5 to 7, the lithium-sulfur battery of Example 1 exhibited a better 890 mAh / g level than Comparative Example 1 after 10 cycles, 30 cycles, and 60 cycles due to the adsorption effect of polysulfide by PTMA Respectively.
[부호의 설명][Description of Symbols]
10. 리튬 이온10. Lithium ion
20. 리튬 폴리설파이드20. Lithium polysulfide
100. 분리막100. The membrane
110. 분리막 본체110. A membrane-
120. 흡착층120. Adsorption layer
200. 양극200. Anode
300. 음극300. Cathode
400. 전해질400. electrolyte
본 발명의 리튬-황 전지는 폴리설파이드의 확산을 억제함으로써, 전극 로딩 및 초기 방전 용량을 개선함은 물론, 최종적으로 리튬-황 전지의 에너지 밀도가 증가된다. 그 결과 상기 리튬-황 전지는 고밀도 전지 또는 고성능 전지로서 바람직하게 적용이 가능하다.The lithium-sulfur battery of the present invention suppresses the diffusion of polysulfide, thereby improving electrode loading and initial discharge capacity, and ultimately increasing the energy density of the lithium-sulfur battery. As a result, the lithium-sulfur battery is preferably applicable as a high-density battery or a high-performance battery.

Claims (11)

  1. 황-탄소 복합체를 포함하는 양극; A positive electrode comprising a sulfur-carbon composite;
    상기 양극과 대향 배치되는 음극; 및A cathode arranged opposite to the anode; And
    상기 양극과 음극 사이에 개재되는 분리막을 포함하는 리튬-황 전지로서,A lithium-sulfur battery including a separator interposed between the positive electrode and the negative electrode,
    상기 분리막은 분리막 본체; 및 상기 분리막 본체의 적어도 일면에 형성된 리튬 폴리설파이드 흡착층을 포함하고,Wherein the separation membrane comprises a separation membrane body; And a lithium polysulfide adsorption layer formed on at least one side of the separator main body,
    상기 흡착층은 니트록실 라디칼 관능기를 가지는 라디칼 화합물을 포함하는 것을 특징으로 하는 리튬-황 전지.Wherein the adsorbent layer comprises a radical compound having a nitroxyl radical functional group.
  2. 제1항에 있어서,The method according to claim 1,
    상기 라디칼 화합물은 분자 내 니트록실 라디칼 관능기를 가지는 폴리머인 것을 특징으로 하는 리튬-황 전지.Wherein the radical compound is a polymer having an intramolecular nitrosyl radical functional group.
  3. 제2항에 있어서,3. The method of claim 2,
    상기 폴리머는 (메타)아크릴레이트, 아크릴로나이트릴, 무수물, 스타이렌, 에폭시, 아이소시아네이트 및 비닐기로 구성된 군으로부터 선택된 어느 하나의 관능기를 포함하는 단량체로부터 중합된 것을 특징으로 하는 리튬-황 전지.Wherein the polymer is polymerized from a monomer containing at least one functional group selected from the group consisting of (meth) acrylate, acrylonitrile, anhydride, styrene, epoxy, isocyanate and vinyl groups.
  4. 제2항에 있어서,3. The method of claim 2,
    상기 폴리머는 폴리(2,2,6,6-테트라메틸-1-피페리디닐록시-4-일 메타아크릴레이트, 폴리(2,2,6,6- 테트라메틸-1-피페리디닐록시-4-일 비닐에스터, 폴리(TEMPO-치환 노보레인), 폴리(2,2,5,5-테트라메틸피롤리딘-1-옥실-3-일 에틸렌 옥사이드, 폴리[2,3-비스(2,2,6,6-테트라메틸피페리딘-1-옥실-4-옥시파보닐)-5-노보렌], 폴리(테트라메틸피페리디녹시)아크릴아미드 및 이들의 조합으로 이루어진 군에서 선택된 1종 이상인 리튬-황 전지.The polymer may be selected from the group consisting of poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate, poly (2,2,6,6-tetramethyl- 1- piperidinyloxy- Poly (2,3-bis (2, 3, 4, 5-tetramethylpyrrolidine-1-oxyl) , 2,6,6-tetramethylpiperidine-1-oxyl-4-oxyphenyl) -5-norbornene], poly (tetramethylpiperidoxy) acrylamide, and combinations thereof At least one lithium-sulfur battery.
  5. 황-탄소 복합체를 포함하는 양극; A positive electrode comprising a sulfur-carbon composite;
    상기 양극과 대향 배치되는 음극; 및A cathode arranged opposite to the anode; And
    상기 양극과 음극 사이에 개재되는 분리막을 포함하는 리튬-황 전지로서,A lithium-sulfur battery including a separator interposed between the positive electrode and the negative electrode,
    상기 분리막의 일부에 테트라메틸 피페리딘 N-옥실을 포함하는 리튬-황 전지.A lithium-sulfur battery comprising tetramethylpiperidine N-oxyl in a part of the separation membrane.
  6. 제2항에 있어서,3. The method of claim 2,
    상기 폴리머는 폴리(2,2,6,6-테트라메틸-1-피페리디닐록시-4-일 메타아크릴레이트인 것을 특징으로 하는 리튬-황 전지.Wherein the polymer is poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate).
  7. 제1항에 있어서,The method according to claim 1,
    상기 니트록실 라디칼 관능기를 가지는 라디칼 화합물의 함량은 흡착층 총 중량의 80 중량% 이상인 리튬-황 전지.Wherein the content of the radical compound having a nitroxyl radical functional group is at least 80 wt% of the total weight of the adsorbent layer.
  8. 제1항에 있어서,The method according to claim 1,
    상기 흡착층의 두께는 0.1 내지 10㎛ 인 리튬-황 전지.Wherein the thickness of the adsorption layer is 0.1 to 10 占 퐉.
  9. 제1항에 있어서,The method according to claim 1,
    상기 흡착층은 전도성 고분자를 더 포함하는 것을 특징으로 하는 리튬-황 전지.Wherein the adsorption layer further comprises a conductive polymer.
  10. 제9항에 있어서,10. The method of claim 9,
    상기 전도성 고분자는 폴리아닐린(Polyaniline), 폴리피롤(Polypyrrole), 폴리티오펜(Polythiopene), 폴라아줄렌(Polyazulene), 폴리피리딘(Polypyridine), 폴리인돌(Polyindole), 폴리카바졸(Polycarbazole), 폴리아진(Polyazine), 폴리퀴논(Polyquinone), 폴리아세틸렌(Polyacetylene), 폴리셀레노펜(Polyselenophene), 폴리텔루로펜(Polytellurophene), 폴리파라페닐렌(Poly-p-phenylene), 폴리페닐렌비닐렌(Polyphenylene vinylene), 폴리페닐렌설파이드(Polyphenylene sulfide), 폴리에틸렌디옥시티오펜(Polyethylenedioxythiophene), 폴리에틸렌글리콜(Polyethylene glycol) 및 이들의 조합으로 이루어진 군에서 선택된 1종 이상인 리튬-황 전지.The conductive polymer may be at least one selected from the group consisting of polyaniline, polypyrrole, polythiophene, polyazulene, polypyridine, polyindole, polycycarbazole, Polyazines such as Polyazine, Polyazine, Polyquinone, Polyacetylene, Polyselenophene, Polytellurophene, Poly-p-phenylene, Polyphenylene vinylene Wherein the lithium-sulfur battery is at least one selected from the group consisting of polyphenylene sulfide, polyethylene dioxythiophene, polyethylene glycol, and combinations thereof.
  11. 제1항에 따른 리튬-황 전지의 제조방법에 있어서,The method for producing a lithium-sulfur battery according to claim 1,
    상기 분리막은,The separation membrane includes:
    i) 분리막 본체를 준비하는 단계;i) preparing a membrane body;
    ii) 니트록실 라디칼 부위를 가지는 라디칼 화합물을 용매에 혼합하여 용액을 제조하는 단계;ii) preparing a solution by mixing a radical compound having a nitroxyl radical portion in a solvent;
    iii) 상기 용액을 분리막 본체의 적어도 일면에 코팅하는 단계; 및iii) coating the solution on at least one side of the membrane body; And
    iv) 상기 코팅된 분리막을 건조하여 리튬 폴리설파이드 흡착층을 형성하는 단계;iv) drying the coated separator to form a lithium polysulfide adsorption layer;
    를 포함하여 제조되는 것을 특징으로 하는 리튬-황 전지의 제조방법.The method of manufacturing a lithium-sulfur battery according to claim 1,
PCT/KR2018/005189 2017-06-20 2018-05-04 Lithium-sulfur battery WO2018236046A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3624223A4 (en) * 2017-06-20 2020-05-13 LG Chem, Ltd. Lithium-sulfur battery
CN113555646A (en) * 2021-08-10 2021-10-26 大连理工大学 Preparation method of coagulant type lithium-sulfur battery positive electrode side interlayer material

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20120008343A (en) * 2010-07-16 2012-01-30 삼성에스디아이 주식회사 Electrode assembly and rechargeable battery using thereof
US20140272569A1 (en) * 2013-03-15 2014-09-18 GM Global Technology Operations LLC Coating for separator or cathode of lithium-sulfur or silicon-sulfur battery
US20150303516A1 (en) * 2014-04-18 2015-10-22 Seeo, Inc Polymer composition with olefinic groups for stabilization of lithium sulfur batteries
KR20160146844A (en) 2014-04-18 2016-12-21 시오 인코퍼레이티드 Long cycle-life lithium sulfur solid state electrochemical cell
KR20170077983A (en) 2015-12-29 2017-07-07 에스케이플래닛 주식회사 User equipment, control method thereof and computer readable medium having computer program recorded thereon
KR20180051030A (en) 2016-11-08 2018-05-16 세메스 주식회사 Apparatus for Droplet Formation and Apparatus for Processing Substrate having the same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20120008343A (en) * 2010-07-16 2012-01-30 삼성에스디아이 주식회사 Electrode assembly and rechargeable battery using thereof
US20140272569A1 (en) * 2013-03-15 2014-09-18 GM Global Technology Operations LLC Coating for separator or cathode of lithium-sulfur or silicon-sulfur battery
US20150303516A1 (en) * 2014-04-18 2015-10-22 Seeo, Inc Polymer composition with olefinic groups for stabilization of lithium sulfur batteries
KR20160146844A (en) 2014-04-18 2016-12-21 시오 인코퍼레이티드 Long cycle-life lithium sulfur solid state electrochemical cell
KR20170077983A (en) 2015-12-29 2017-07-07 에스케이플래닛 주식회사 User equipment, control method thereof and computer readable medium having computer program recorded thereon
KR20180051030A (en) 2016-11-08 2018-05-16 세메스 주식회사 Apparatus for Droplet Formation and Apparatus for Processing Substrate having the same

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
CHANG, CHI-HAO ET AL.: "Ultra-lightweight PANiNF/MWCNT-functionalized Separators with Synergistic Suppression of Polysulfide Migration for Li-S Batteries with Pure Sulfur Cathodes", JOURNAL OF MATERIALS CHEMISTRY A., vol. 3, 2015, pages 18829 - 18834, XP055554890 *
HONGWEI CHENACHANGHONG WANGAYAFEI DAIBJUN GEAWEI LUALIWEI CHEN: "In-situ activated polycation as a multifunctional additive for Li-S batteries", NANO ENERGY, vol. 26, 2016, pages 43 - 49
MA, GUOQIANG ET AL.: "Enhanced Performance of Lithium Sulfur Battery with Self-assembly Polypyrrole Nanotube Film as the Functional Interlayer", JOURNAL OF POWER SOURCES, vol. 273, pages 511 - 516, XP029092199 *
See also references of EP3624223A4

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3624223A4 (en) * 2017-06-20 2020-05-13 LG Chem, Ltd. Lithium-sulfur battery
US11545720B2 (en) 2017-06-20 2023-01-03 Lg Energy Solution, Ltd. Lithium-sulfur battery
CN113555646A (en) * 2021-08-10 2021-10-26 大连理工大学 Preparation method of coagulant type lithium-sulfur battery positive electrode side interlayer material
CN113555646B (en) * 2021-08-10 2022-04-19 大连理工大学 Preparation method of coagulant type lithium-sulfur battery positive electrode side interlayer material

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