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Electrochemical Characteristics of Supercapacitor Using Ionic Liquid Electrolyte

Supercapacitor용 이온성 액체 전해질의 전기화학적 특성

  • 김상길 (비츠로셀) ;
  • 황갑진 (호서대학교 일반대학원 그린에너지공학과) ;
  • 김재철 (호서대학교 일반대학원 그린에너지공학과) ;
  • 유철휘 (호서대학교 일반대학원 그린에너지공학과)
  • Received : 2011.11.03
  • Accepted : 2011.11.14
  • Published : 2011.11.30

Abstract

Supercapacitor has been studied actively as one of the most promising electrochemical energy storage system for a wide range of applications. To increase the energy density of supercapacitor, the introduction of ionic liquids is required. In this study, two types of EMI-$BF_4$ based on quaternary imidazolium salt were prepared with quaternary reaction and anion exchange. The structural characterization and thermal stability were analyzed by nuclear magnetic resonance($^1H$-NMR) and thermogravimetric analysis(TGA), respectively. Thermal stability of the EMI-$BF_4$ using TGA confirmed that, after heat treatment, the decomposition temperature of EMI-$BF_4$ was increased. Supercapacitors were fabricated with synthesized and commercial ionic liquids, and charge/discharge characteristics were also investigated. The capacity of supercapacitor, for synthesized and commercial EMI-$BF_4$ were determined to be 0.067 F and 0.073 F respectively, by means of charge/discharge test.

수퍼커패시터는 다양한 응용범위를 갖는 유망한 에너지 저장장치로서 활발히 연구되고 있으며, 에너지 밀도 향상을 위하여 이온성 액체의 적용이 필요하다. 본 연구에서는 4급화 반응과 음이온 교환반응을 거쳐 4급 imidazolium 염을 생성하는 반응으로 두 종류의 EMI-$BF_4$를 합성하였다. $^1H$-NMR을 통하여 EMI-$BF_4$의 합성을 확인하였고 TGA를 통하여 열적안정성을 확인하였으며, 이때 합성된 이온성 액체를 열처리한 경우 열적 안정성이 향상되었다. LSV를 통하여 본 연구에서 합성한 EMI-$BF_4$가 4 V 이상의 넓은 전위창을 가지고 있어, 기존의 전해질 대비 우수한 전기화학적 안정성을 가지고 있음을 확인하였다. 충방전 실험 결과 본 실험에서 합성한 이온성 액체를 상용화 제품과 비교한 경우 용량은 각각 0.067 F 및 0.073 F로 측정되었다.

Keywords

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