화학공학소재연구정보센터
Journal of the Korean Industrial and Engineering Chemistry, Vol.13, No.8, 793-798, December, 2002
Poly[(ethylene glycol) diacrylate]-Poly(vinylidene fluoride) 전해질을 이용한 전기 이중층 캐패시터의 전기화학적 특성
Electrochemical Characteristics of EDLC with Poly[(ethylene glycol) diacrylate]-Poly(vinylidene fluoride) Electrolyte
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초록
자외선 경화법으로 제조한 PEGDA-PVdF 젤상 고분자 전해질을 전기이중층캐패시터에 적용하였고, 액상 유기 전해질을 이용한 전기이중층캐패시터와 전기화학적 특성을 비교 조사하였다. 자외선 경화법으로 제조된 젤상 고분자 전해질[GPE:poly[(ethylene glycol) diacrylate] -poly(vinylidene fluoride) blend]을 이용한 전기이중층캐패시터의 경우, 비축전용량이 120 F/g으로 액상 유기 전해질[LOE: 1M LiPF6/EC : DMC: EMC (1:1:1 volume ratio)]을 이용한 전기이중층캐패시터의 비축전용량인 110 F/g보다 우수하였고, 100회 충방전 후에도 초기 비축전용량대비 92% 이상 유지하는 우수한 싸이클 특성을 나타내었으며 3.7 Ω의 낮은 ESR(equivalent series resistance)을 보여주었다. Cyclic voltammetry 분석 결과에서 보면 액상 유기 전해질과 젤상 고분자 전해질을 이용한 모든 전기이중층캐패시터에서 2.5 V까지 전해질의 분해 없이 전기화학적으로 안정하였고, 산화와 환원과 관련된 전류값 또한 관찰되지 않았다. 젤상 고분자 전해질을 이용한 전기이중층캐패시터의 경우에서 직사각형 모양의 이상적인 전기이중층캐패시터의 특성과 49 μA의 낮은 누설 전류값을 나타내었다. 자가방전 특성 결과, 젤상 고분자 전해질을 이용한 전기이중층캐패시터의 경우 2.5 V의 정전압 충전 시 OCV(open circuit voltage) 상태에서 100 h 경과 후 1.76 V의 전압을 유지하고 있어 0.25 V의 액상 유기 전해질을 이용한 전기이중층캐패시터보다 매우 우수함을 확인하였다.
Poly[(ethylene glycol) diacrylate] (PEGDA)-Poly(vinylidene fluoride) (PVdF) gel polymer was employed as an electrolyte for electric double layer capacitor (EDLC) and compared its electrochemical characteristics with that of liquid organic electrolyte. The used organic electrolyte was 1 mode of lithium hexafluorophosphate (LiPF6) salt containing in the solvent mixture of ethylene carbonate(EC): dimethyl carbonate(DMC): ethylmethyl carbonate(EMC)(1:1:1 volume ratio). The specific capacitance of EDLC with gel polymer electrolyte showed 120 F/g, which was superior to that of 110 F/g with liquid organic electrolyte. Good cyclability was observed for gel polymer electrolyte of EDLC. The 92% of initial specific capacitance was retained after 100 cycles of charge-discharge runs. Equivalent series resistance of 3.7 Ω of the EDLC with gel polymer electrolyte was lower than that of EDLC with liquid organic electrolyte. The EDLC with gel polymer electrolyte exhibited rectangular cyclic voltammogram of ideal EDLC in operating voltage range of 0 ~ 2.5 V and low leakage current of 49 μA. Voltage drop from self-discharge was low for gel polymer electrolyte. The 29.6% of initial voltage decreased for gel polymer electrolyte, but significantly dereased to 99% for liquid organic electrolyte. The good retentivity with gel polymer electrolyte possibly comes from the difference in viscosity compared with that of liquid organic electrolyte.
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