KR20150004179A - An electrolyte for lithium sulfur battery - Google Patents
An electrolyte for lithium sulfur battery Download PDFInfo
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- KR20150004179A KR20150004179A KR1020130077322A KR20130077322A KR20150004179A KR 20150004179 A KR20150004179 A KR 20150004179A KR 1020130077322 A KR1020130077322 A KR 1020130077322A KR 20130077322 A KR20130077322 A KR 20130077322A KR 20150004179 A KR20150004179 A KR 20150004179A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0569—Liquid materials characterised by the solvents
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/581—Chalcogenides or intercalation compounds thereof
- H01M4/5815—Sulfides
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
본 발명은 리튬황 전지의 전해질로 이용되는 고분자 화합물에 관한 것이며, 더욱 상세하게는 디메틸 에테르를 리튬황 전지의 전해질로 이용하는 것에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a polymer compound used as an electrolyte of a lithium sulfur battery, and more particularly to the use of dimethyl ether as an electrolyte of a lithium sulfur battery.
휴대용 전자기기의 급속한 발전에 따라 2차 전지의 수요를 증가시키고 있다. 휴대용 전자기기의 경박단소의 추세에 부응할 수 있는 고에너지 밀도의 전지의 등장이 지속적으로 요구되고 있으며, 이러한 요구에 부응하기 위해서는 값싸고 안전하고 환경 친화적인 면을 만족하는 전지의 개발이 필요하다.With the rapid development of portable electronic devices, the demand for secondary batteries is increasing. In order to meet such a demand, it is necessary to develop a battery which satisfies the cheap, safe and environmentally-friendly aspects in order to meet the demand of high energy density battery which can meet the trend of light and small size of portable electronic devices .
이러한 욕구를 만족시키는 여러 가지 전지들 중에 리튬황 전지는 현재까지 개발되고 있는 전지 중 에너지 밀도 면에서 가장 유망하며, 리튬의 에너지 밀도는 3830mAh/g, S8의 에너지 밀도가 1675mAh/g으로서, 활물질로 사용되는 원료가 저렴하며 환경친화적인 2차 전지 시스템이다.Among the various batteries satisfying this need, lithium sulphate is the most promising in terms of energy density among the batteries developed so far. The energy density of lithium is 3830 mAh / g and the energy density of S 8 is 1675 mAh / g. Is an inexpensive and eco-friendly secondary battery system.
한편, 리튬황 전지의 상용화 문제에 있어서, 산화환원 반응시에 황이 전해액으로 유출되어 야기되는 전지 수명의 열화 및 적절한 전해액을 선택하지 못한 경우 황의 환원 물질인 리튬설파이드(Li2S)가 석출되어 황이 더 이상 전기화학 반응에 참여하지 못하게 되는 문제점이 발생한다.On the other hand, in the problem of commercialization of the lithium sulfur battery, in the case of deterioration of the life of the battery caused by outflow of sulfur into the electrolyte solution during the redox reaction and in case of failing to select an appropriate electrolyte solution, lithium sulfide (Li 2 S) There arises a problem that it is no longer possible to participate in the electrochemical reaction.
미국특허공보 제 6,030,720호에서는 전해액에 투입되는 주용매로서 R1-(CH2-CH2-O)n-R2 (n은 2 내지 10, R은 알킬 또는 알콕시 그룹), 공용매로서 도우너(donor)넘버가 15 이상인 용매를 혼합하여 사용한다. 또한, 크라운 에테르, 크립탠드 및 도우너 용매 중 하나 이상을 포함하는 전해액을 사용한다.In U.S. Patent No. 6,030,720, R 1 - (CH 2 -CH 2 -O) n -R 2 (n is 2 to 10, R is an alkyl or alkoxy group) as a main solvent to be fed into an electrolytic solution, donor) number of 15 or more. Also, an electrolyte solution containing at least one of crown ether, kryptand and donor solvent is used.
미국특허공보 제5,961,672호에서는 리튬 재질의 애노드에 고분자 필름의 피막을 형성하여 리튬전지의 수명과 안전성을 개선시키고 있는데, 그 수단으로 1M LiSO3-CF3, 1,3-디옥소란계 화합물/디그라임/설포란/디메톡시에탄을 50:20:10:20의 비율로 혼합한 용액을 전해액으로 사용한 것을 제시하고 있다.U.S. Patent No. 5,961,672 discloses a method for improving the lifetime and safety of a lithium battery by forming a film of a polymer film on an anode made of a lithium material. As a means thereof, 1M LiSO 3 -CF 3 , 1,3-dioxolane compound / And a solution prepared by mixing diglyme / sulfolane / dimethoxyethane in a ratio of 50: 20: 10: 20 as an electrolyte solution.
공개 제10-2004-0043226호는,Open No. 10-2004-0043226,
리튬염과 유기용매로 이루어진 리튬 설퍼 전지용 유기 전해액에 있어서, 상기 유기용매가 화학식 1로 표시되는 화합물 또는 그 이성질체를 포함하는 것을 특징으로 하는 리튬 설퍼 전지용 유기 전해액을 개시한다:An organic electrolytic solution for a lithium sulfur battery comprising a lithium salt and an organic solvent, wherein the organic solvent comprises a compound represented by the formula (1) or an isomer thereof:
<화학식 1>≪ Formula 1 >
R1-CH2-CH2-CH2-R2 R 1 -CH 2 -CH 2 -CH 2 -R 2
상기 화학식 중 R1 및 R2 는 서로에 관계없이 할로겐 원자, 하이드록시기, 치환된 또는 비치환된 탄소수 1 내지 20의 알킬기, 치환된 또는 비치환된 탄소수 1 내지 20의 알콕시기, 치환된 또는 비치환된 탄소수 6 내지 30의 아릴기, 치환 또는 비치환된 C6 내지 C30의 아릴알킬기, 치환된 또는 비치환된 탄소수 6 내지 30의 아릴옥시기, 치환된 또는 비치환된 탄소수 2 내지30의 헤테로아릴기, 치환 또는 비치환된 C2 내지 C30의 헤테로아릴알킬기, 치환된 또는 비치환된 탄소수 2 내지 30의 헤테로아릴옥시기, 치환 또는 비치환된 C5 내지 C20의 사이클로알킬기 또는 치환 또는 비치환된 C2 내지 C20의 헤테로사이클로알킬기이다.Wherein R 1 and R 2 are independently selected from the group consisting of a halogen atom, a hydroxy group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, A substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted C2 to 30 hetero A substituted or unsubstituted C2 to C30 heteroarylalkyl group, a substituted or unsubstituted C2 to C30 heteroaryloxy group, a substituted or unsubstituted C5 to C20 cycloalkyl group, or a substituted or unsubstituted C2 To C20 heterocycloalkyl groups.
한편, DME(dimethyl ether)를 리튬황 전지의 전해질로 이용하는 경우, 다른 에테르계 용매 (TEGDME(tetraethylene glycol dimethyl ether), DEGDME(diethylene glycol dimethyl ether) 등)를 이용한 경우보다, 배터리의 충방전 특성이 우수하다고 알려진 바 있다. [리튬/유황전지용 유황양극의 사이클 특성에 미치는 전해질의 영향, 박진우, 경상대 학위논문] On the other hand, when DME (dimethyl ether) is used as the electrolyte of the lithium sulfur battery, the charge / discharge characteristics of the battery are lower than those of other ether solvents (TEGDME, DEGDME, It is known to be excellent. [ Effect of Electrolytes on the Cycle Characteristics of Sulfur Anodes for Lithium / Sulfur Batteries, Jinwoo Park,
그러나 DME의 경우 끓는점, 발화점이 낮아 고온 안정성이 취약하다는 어려운 문제가 있다. 하기 표 1을 참조한다.However, in the case of DME, there is a problem that the boiling point and the ignition point are low and the high-temperature stability is weak. See Table 1 below.
(dimethyl ether)DME
(dimethyl ether)
(diethylene glycol
dimethylether)DEGDME
diethylene glycol
dimethylether)
따라서 본 발명에서는 DME의 발화점을 높이는 Sulfolane을 첨가한 리튬황 전지용 신규 전해질을 제공하고자 한다.Accordingly, the present invention provides a novel electrolyte for a lithium sulfur battery to which sulfolane is added to increase the ignition point of DME.
본 발명은,According to the present invention,
애노드 활성 물질을 포함하는 음극(애노드), 황 또는 황화합물을 캐소드 활성물질로 포함하는 양극(캐소드), 및 액체 또는 겔 전해질 용액을 함유하는 리튬황 전지의 전해질 조성물에 있어서, 상기 전해질 조성물은 0.8 내지 1.2 M의 LiTFSI(lithium trifluoromethanesulfonimide) 를 함유하는 것이고, 상기 LiTFSI 는 DME와 Sulfolane의 혼합물인 것을 특징으로 하는 조성물을 제공한다.
1. An electrolyte composition for a lithium sulfur battery comprising a cathode (anode) comprising an anode active material, a cathode (cathode) comprising sulfur or a sulfur compound as a cathode active material, and a liquid or gel electrolyte solution, 1.2 M LiTFSI (lithium trifluoromethanesulfonimide), and the LiTFSI is a mixture of DME and Sulfolane.
또한 본 발명은,Further, according to the present invention,
상기의 DME : Sulfolane의 몰비가 4:6~8:2, 7:3, 또는 1:1 인 것을 특징으로 하는 조성물을 제공한다.
Wherein the molar ratio of DME to Sulfolane is from 4: 6 to 8: 2, 7: 3, or 1: 1.
TEGDME 및DIOX 전해질에서 제조된 셀과 본 발명의 전해질로 제조된 셀과의 충방전 결과, 본 발명의DME:Sulfolane이 1:1인 전해질을 이용한 셀의 경우 TEGDME 기반 전해질 이용한 셀 대비 용량, 수명 향상 및 고온 안정성이 개선되었다.As a result of charging / discharging between the cell made of TEGDME and DIOX electrolyte and the cell made of the electrolyte of the present invention, the capacity and lifetime of the cell using electrolyte of 1: 1 DME: Sulfolane of the present invention using TEGDME based electrolyte And improved high temperature stability.
한편, 본 발명의DME:Sulfolane이 7:3인 전해질을 이용한 셀의 경우 TEGDME 기반 전해질 이용한 셀 대비 용량, 수명 향상 및 고온 안정성이 더욱 개선되었다.
On the other hand, in the case of the cell using DME: Sulfolane of 7: 3 according to the present invention, the capacity, lifetime and high temperature stability of the cell using the TEGDME based electrolyte were further improved.
본 발명의 술포란 및 디메틸 에테르의 화학식은 다음과 같다.The formula of sulfolane and dimethyl ether of the present invention is as follows.
본 발명은,According to the present invention,
애노드 활성 물질을 포함하는 음극(애노드), 황 또는 황화합물을 캐소드 활성물질로 포함하는 양극(캐소드), 및 액체 또는 겔 전해질 용액을 함유하는 리튬황 전지의 전해질 조성물에 있어서, 상기 전해질 조성물은 0.8 내지 1.2 M의 LiTFSI(lithium trifluoromethanesulfonimide) 를 함유하는 것이고, 상기 LiTFSI 는 DME와 Sulfolane의 혼합물인 것을 특징으로 하는 조성물을 제공한다.
1. An electrolyte composition for a lithium sulfur battery comprising a cathode (anode) comprising an anode active material, a cathode (cathode) comprising sulfur or a sulfur compound as a cathode active material, and a liquid or gel electrolyte solution, 1.2 M LiTFSI (lithium trifluoromethanesulfonimide), and the LiTFSI is a mixture of DME and Sulfolane.
또한 본 발명은,Further, according to the present invention,
상기의 DME : Sulfolane의 몰비가 4:6~8:2, 7:3, 또는 1:1 인 것을 특징으로 하는 조성물을 제공한다.
Wherein the molar ratio of DME to Sulfolane is from 4: 6 to 8: 2, 7: 3, or 1: 1.
상기 4:6~8:2의 수치 한정의 임계적 의의는 다음과 같다.The critical significance of the numerical limitation of 4: 6 to 8: 2 is as follows.
DME: Sulfolane=4:6이 바람직한 이유는 DME가 위 수치보다 적게 들어가면 용량이 매우 낮아지는 문제가 있어 DME비율을 4 이상으로 해야하기 때문이다. The reason why DME: Sulfolane = 4: 6 is preferable is because when the amount of DME is less than the above value, the capacity is very low and the DME ratio should be 4 or more.
한편, DME: Sulfolane= 8:2보다 DME 수치가 높아지면 즉 예를 들면 9:1 같이 되면 Sulfolane 효과가 미미해서 끓는점 향상되는 효과가 없으므로 Sulfolane 비율을 2 이상으로 해야 한다.
On the other hand, when the DME value is higher than that of DME: Sulfolane = 8: 2, for example, when the DME value is increased to 9: 1, the sulfolane effect is insignificant and the boiling point is not improved.
상기 리튬염은 전해액에 리튬 이온을 제공하는 역할을 하는 것으로써, 육플루오르화인산 리튬(LiPF6), 육플루오르화비산 리튬(LiAsF6), 과염소산리튬(LiClO4), 리튬 비스(트리플루오로메탄 술포닐)이미드(LiN(CF3SO2)2, LiTFSI), 삼플루오로술폰산 리튬(LiCF3SO3), 또는 그외의 리튬염으로 이루어지는 군으로부터 선택될 수 있다. 바람직하게는 LiTFSI 이며, 바람직한 이유는 이온전도도, 안정성 등이 리튬황 전지에 이용되는 ether 계 용매에 가장 적절하다고 알려져 있기 때문이다.The lithium salt serves to provide lithium ions to the electrolytic solution. The lithium salt serves to supply lithium ions to the electrolytic solution. The lithium salt may be used in combination with lithium hexafluorophosphate (LiPF 6 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium perchlorate (LiClO 4 ) methanesulfonyl) may already be selected from de (LiN (CF 3 SO 2) 2, LiTFSI), lithium tri sulfonate (LiCF 3 SO 3), or the group consisting of the lithium salt of the other fluoro. Preferably LiTFSI, and it is preferable that ion conductivity, stability and the like are most suitable for ether solvents used in lithium sulfur batteries.
상기 캐소드 활성 물질은, 바인더 및 전기 전도성 물질을 추가로 포함할 수 있다. 바인더 물질은 PVDF (Polyvinylidene fluoride ) + HFC (Difluoroethane) 혼합액, PVDF, 카본블랙 (carbon black)등이 가능하며, 전기 전도성 물질은 VGCF (Vapor grown carbon fibers), 그라파이트(graphite), 카본나노튜브(CNT) 등이 가능하다. 바람직하게는 PVDF + HFC 혼합액과 VGCF를 추가할 수 있으며, 바람직한 이유는 PVDF+HFC 혼합액의 경우 전기화학적, 열적 안정성이 우수하며, 분자량이 높아 적은 양만 사용 가능하기 때문이며, VGCF의 경우 전도성과 강도가 우수하기 때문이다.The cathode active material may further include a binder and an electrically conductive material. The binder material may be PVDF (polyvinylidene fluoride) + HFC (Difluoroethane) mixture liquid, PVDF, carbon black, etc. The electrically conductive material may include VGCF (VGCF), graphite, carbon nanotube ). Preferably, PVDF + HFC mixed solution and VGCF can be added. The reason for this is that the PVDF + HFC mixed solution is excellent in electrochemical and thermal stability and can be used only in a small amount because of high molecular weight. In case of VGCF, Because it is excellent.
이하 본 발명을 하기 구체적인 실험예로 더욱 상세히 설명하고자 하며, 하기 실험은 본 발명의 일례일 뿐, 본 발명의 범위가 이에 한정되는 것은 아니다.Hereinafter, the present invention will be described in more detail with reference to the following experimental examples. The following experiments are merely examples of the present invention, but the scope of the present invention is not limited thereto.
DMEDME : : SulfolaneSulfolane = 1:1인 = 1: 1 실시예Example
실시예Example
DME : Sulfolane = 1:1인 1M의 LiTFSI 전해질 용액을 제조한다. A 1 M LiTFSI electrolyte solution with DME: Sulfolane = 1: 1 is prepared.
비교예Comparative Example
TEGDME : DIOX = 1:1인 1M의 LiTFSI 전해질 용액을 제조한다. 첨가제로 0.2 M의 LiNO3를 사용하였다.TEGDME: DIOX = 1: 1 is prepared. 0.2 M of LiNO 3 was used as an additive.
TEGDME ; tetraethylene glycol dimethyl ether , DIOX ; dioxolaneTEGDME; tetraethylene glycol dimethyl ether, DIOX; dioxolane
셀의 제작Cell creation
셀직경 20Ø인 코인셀을 제작하였다.A coin cell with a cell diameter of 20 was prepared.
양극은, 황 로딩양 4.9 mg/㎠이 되도록 미분황과 도전재, 바인더를 혼합하여 볼밀링 법을 이용하여 제조하였고, 이때 전극두께는 0.5mm이다.The anode was prepared using a ball milling method in which a sulfur-loaded amount of 4.9 mg / cm 2 was mixed with a finely divided sulfur, a conductive material and a binder, and the electrode thickness was 0.5 mm.
음극은, Li metal (순수한 리튬으로 이루어진 리튬 포일) 을 두께 0.7 mm로 제작하였다.The cathode was made of Li metal (lithium foil made of pure lithium) with a thickness of 0.7 mm.
충방전 실험Charge-discharge experiment
C rate는 0.05C, 충방전 전위는 1.5 ~ 2.65V이었다.C rate was 0.05C, and charge / discharge potential was 1.5 ~ 2.65V.
열적 안정성 평가Evaluation of thermal stability
1) TGA(Thermal Gravitic Analysis) : 열중량 분석 1) TGA (Thermal Gravitic Analysis): Thermogravimetric analysis
물질의 온도를 조정된 프로그램에 따라 변화시키면서 그 물질의 질량을 온도의 함수로서 측정하는 방법이며, 끓는점, 녹는점 분석에 이용한다.A method of measuring the mass of a substance as a function of temperature while varying the temperature of the material according to a regulated program, and is used for boiling point and melting point analysis.
2) 시차주사열량계 (DSC) 2) Differential Scanning Calorimetry (DSC)
물질과 기준물질의 온도를 조정된 프로그램에 따라 변화시켜 가면서 그 물질과 기준 물질에 대한 에너지 입력의 차를 온도의 함수로서 측정하는 방법, 즉 온도를 변화시켜 가면서 시료로부터 또는 시료로 흐른 열의 양을 측정하는 방법이다. A method of measuring the difference between the energy input of a substance and a reference substance as a function of temperature while changing the temperature of the substance and the reference material in accordance with a controlled program, that is, the amount of heat flowing from the sample to the sample .
원리는, 시료와 기준물질을 각각의 가열로에 넣고 일정한 속도로 온도를 올렸을 때 시료가 흡열하면 그와 똑같은 전기에너지를 시료의 가열로에 공급하며 발열을 하면 발열에 해당되는 만큼의 전기에너지를 기준물질의 가열로에 공급하여 두개의 가열로 안의 시료 접시 온도를 항상 같게 하여 출입열량의 변화를 측정하여 온도의 함수로 나타내는 것이다.
The principle is that when the sample and the reference material are put into each heating furnace and the temperature is raised at a constant rate, when the sample absorbs the heat, the same electric energy is supplied to the heating furnace of the sample. And the temperature of the sample plate in each of the two heating furnaces is always equal to that of the reference furnace.
발명의 효과 Effects of the Invention
DME:Sulfolane 전해질 이용한 셀의 경우 TEGDME 전해질 이용한 셀 대비 용량 및 수명 향상 및 고온 안정성 개선되었다.In the case of DME: Sulfolane electrolyte, the capacity and lifetime of the cell using TEGDME electrolyte was improved and the stability at high temperature was improved.
충방전 실험 결과 본 발명의 전해질 (DME:Sulfolane)을 이용한 경우, 비교예의 전해질 (TEGDME:DIOX) 대비 높은 용량 유지 확인하였는바, 20th cycle 기준 본 발명의 전해질은 약 500 mAh/g, 비교예의 전해질은 약 300 mAh/g (기존대비 67% 향상)로 나타났다.
When the electrolyte (DME: Sulfolane) according to the present invention was used, it was confirmed that the capacity of the electrolyte according to the comparative example (TEGDME: DIOX) was maintained at a high level. As a result, the electrolyte of the present invention based on 20th cycle was about 500 mAh / g, Was about 300 mAh / g (67% higher than the previous one).
본 발명의 전해질의 우수한 충방전 특성 원인으로서 DME의 분자량과 점도가 낮아, 이온 이동을 원활히 하여 높은 용량을 얻게 되는 것이다.As a cause of excellent charge / discharge characteristics of the electrolyte of the present invention, the molecular weight and viscosity of DME are low, so that ion migration is facilitated and high capacity is obtained.
열적 안정성 평가 결과는 다음과 같았다.The results of the thermal stability evaluation were as follows.
1) 끓는점 평가 : TGA 평가방법 이용1) Boiling point evaluation: Using TGA evaluation method
Sulfolane을 DME에 1:1로 혼합한 본 발명의 전해질의 TGA 평가 결과 끓는점 97 ℃ 로 상승하였다. As a result of TGA evaluation of the electrolyte of the present invention in which sulfolane was mixed with DME at a ratio of 1: 1, the boiling point was raised to 97 占 폚.
2) 발화점 평가 : DSC 평가방법 이용2) Evaluation of flash point: Using DSC evaluation method
Sulfolane을 DME에 1:1로 섞은 전해질과 양극(황전극)을 혼합하여 DSC 평가한 결과 기존 -6 ℃ 에서 20 ℃ 로 상승하였다.
Sulfolane was mixed with DME at a ratio of 1: 1 and an anode (sulfur electrode) was mixed.
DMEDME : : SulfolaneSulfolane = 7:3인 = 7: 3 실시예Example
실시예 (조건 3)Example (Condition 3)
DME : Sulfolane = 7:3인 1M의 LiTFSI 전해질 용액을 제조한다.DME: Sulfolane = 7: 3 is prepared.
비교예 1 (조건 1) 및 비교예 2(조건 2)Comparative Example 1 (Condition 1) and Comparative Example 2 (Condition 2)
DME : Sulfolane = 3:7 (조건 1) 및 5:5 (조건 2)인 1M의 LiTFSI 전해질 용액을 제조한다.DME: Sulfolane = 3: 7 (condition 1) and 5: 5 (condition 2).
셀의 제작Cell creation
전극 직경 16Ø인 코인셀을 제작하였다.A coin cell having an electrode diameter of 16 was prepared.
양극은, 황 로딩양 4.9 mg/㎠이 되도록 미분황과 도전재, 바인더를 혼합하여 볼밀링 법을 이용하여 제조하였고, 이때 전극두께는 0.5mm이다. (이용한 황의 형태는 1:1 실시예와 동일 조건으로 제작)The anode was prepared using a ball milling method in which a sulfur-loaded amount of 4.9 mg / cm 2 was mixed with a finely divided sulfur, a conductive material and a binder, and the electrode thickness was 0.5 mm. (The sulfur used was produced under the same conditions as in the 1: 1 example)
음극은, Li foil을 두께 0.7 mm로 제작하였다.The cathode was made of Li foil with a thickness of 0.7 mm.
전해질의 양은 약 140ml를 사용하였다.The amount of electrolyte was about 140 ml.
충방전 실험Charge-discharge experiment
C rate는 0.05C, 충방전 전위는 1.5 ~ 2.65V이었다.C rate was 0.05C, and charge / discharge potential was 1.5 ~ 2.65V.
발명의 효과 Effects of the Invention
조건1Condition 1
용량(mAh/g)은 20th cycle기준으로 560, 가장 낮은 용량을 보였다.The capacity (mAh / g) was 560 at 20th cycle and the lowest capacity.
10th cycle 이후 용량 증가 원인은 사이클 진행에 따라 전극에 균열 발생하고, 그 균열에서 노출된 황이 충방전 반응에 참여했기 때문이다.The capacity increase after the 10th cycle is due to cracks in the electrodes due to the progress of the cycle, and the exposed sulfur in the cracks participated in the charge / discharge reaction.
순간적으로는 용량 증가되는 것처럼 보일 수 있으나, 장기적 관점에서 현 전극은 수명 특성이 나쁠 것이다. The capacity may seem to increase momentarily, but in the long term the current electrode will have poor life characteristics.
조건2Condition 2
용량(mAh/g)은20th cycle기준으로 580, 초기용량은 가장 높으나 이후 용량 급감 현상 보인다.Capacity (mAh / g) is 580 on 20th cycle basis, and the initial capacity is the highest, but thereafter the capacity decrease appears.
조건3Condition 3
용량(mAh/g)은 20th cycle기준으로 670, 용량 가장 높고, 수명특성도 가장 높다.Capacity (mAh / g) is 670, based on 20th cycle, and has the highest capacity and life characteristics.
그 이유는, DME는 에테르계 용매 중 배터리 충방전 특성을 가장 우수하게 발현하는 전해질이므로, DME이 양이 가장 많은 조건3에서 가장 우수한 특성을 보인 것으로 생각된다. 그러나 DME의 경우 발화점 및 끓는점이 낮아 실제로 배터리에 적용되기는 어려운데, Sulfolane을 첨가함으로써 해당 문제가 해결되었다.The reason for this is that DME is the electrolyte which exhibits the best charge / discharge characteristics of the battery among ether solvents, and therefore, DME is considered to be the most excellent in the condition 3 in which the amount is the greatest. However, in case of DME, it is difficult to apply to battery because it has low flash point and boiling point, and the problem is solved by adding sulfolane.
한편 Sulfolane은 에너지 준위상 LUMO 에너지가 낮아 환원반응성이 높고, 때문에 음극 분해를 촉진하고 이때 음극에 보호막이 형성되는 역할을 한다. 그러나 Sulfolane 과다 첨가되면 보호막 형성반응 외에 악영향을 끼치는 부반응도 함께 발생되므로 Sulfolane을 첨가하되 적정량(소량) 첨가하는 것이 중요하다. 따라서 7:3의 비율이 가장 효과적이다.
On the other hand, Sulfolane has a low energy-sub-phase LUMO energy and is highly reactive and thus accelerates the decomposition of the negative electrode and forms a protective film on the negative electrode. However, when Sulfolane is added excessively, Sulfolane is added, but it is important to add a small amount of Sulfolane because a side reaction that adversely affects the reaction occurs. Therefore, a ratio of 7: 3 is most effective.
Claims (7)
1. An electrolyte composition for a lithium sulfur battery comprising a cathode (anode) comprising an anode active material, a cathode (cathode) comprising sulfur or a sulfur compound as a cathode active material, and a liquid or gel electrolyte solution, 1.2 M of lithium trifluoromethanesulfonimide (LiTFSI), said LiTFSI being a mixture of DME and Sulfolane.
The composition of claim 1, wherein the molar ratio of DME to Sulfolane is from 4: 6 to 8: 2.
The composition of claim 1, wherein the molar ratio of DME: Sulfolane is 7: 3.
The composition of claim 1, wherein the molar ratio of DME: Sulfolane is 1: 1.
The lithium secondary battery according to any one of claims 1 to 4, wherein the anode active material is lithium hexafluorophosphate (LiPF 6 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium perchlorate (LiClO 4 ), lithium bis trifluoromethane sulfonyl) imide (LiN (CF 3 SO 2) 2), a three-fluoro sulfonic lithium (LiCF 3 SO 3), or a composition selected from the group consisting of lithium salts as well.
5. The cathode active material according to any one of claims 1 to 4, wherein the cathode active material is selected from the group consisting of elemental sulfur, lithium polysulfide (Li 2 Sn, where n≥1), inorganic and organic Polymer-based) compounds, and mixtures thereof.
The composition of any one of claims 1 to 4, wherein the cathode active material further comprises a binder and an electrically conductive material.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20170027141A (en) | 2015-09-01 | 2017-03-09 | 한국화학연구원 | Sulfone containing organic electrolyte for lithium-air battery having good energy efficiency and oxygen efficiency and lithium-air battery using the same |
| KR20180124722A (en) | 2017-05-11 | 2018-11-21 | 한국과학기술연구원 | Electrolyte system and lithium metal battery comprising the same |
| KR20190083108A (en) | 2018-01-03 | 2019-07-11 | 한국과학기술연구원 | Electrolyte system and lithium metal battery comprising the same |
| KR20190083109A (en) | 2018-01-03 | 2019-07-11 | 한국과학기술연구원 | Electrolyte system and lithium metal battery comprising the same |
| US10804567B2 (en) | 2017-05-11 | 2020-10-13 | Korea Institute Of Science And Technology | Electrolyte system for lithium metal secondary battery and lithium metal secondary battery including the same |
-
2013
- 2013-07-02 KR KR1020130077322A patent/KR20150004179A/en active Search and Examination
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20170027141A (en) | 2015-09-01 | 2017-03-09 | 한국화학연구원 | Sulfone containing organic electrolyte for lithium-air battery having good energy efficiency and oxygen efficiency and lithium-air battery using the same |
| KR20180124722A (en) | 2017-05-11 | 2018-11-21 | 한국과학기술연구원 | Electrolyte system and lithium metal battery comprising the same |
| US10804567B2 (en) | 2017-05-11 | 2020-10-13 | Korea Institute Of Science And Technology | Electrolyte system for lithium metal secondary battery and lithium metal secondary battery including the same |
| KR20190083108A (en) | 2018-01-03 | 2019-07-11 | 한국과학기술연구원 | Electrolyte system and lithium metal battery comprising the same |
| KR20190083109A (en) | 2018-01-03 | 2019-07-11 | 한국과학기술연구원 | Electrolyte system and lithium metal battery comprising the same |
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