Preparation and Electrochemical Behaviors of Polymer Electrolyte Based on PEO/PMMA Containing Li Ion

Li 이온 포함하는 PEO/PMMA 고분자 전해질의 제조 및 전기화학적 거동

  • Han, A-Reum (Dept. of Chemistry, Chungbuk National Univ.) ;
  • Park, Soo-Jin (Dept. of Chemistry, Inha University) ;
  • Shin, Jae-Sup (Dept. of Chemistry, Chungbuk National Univ.) ;
  • Kim, Seok (Dept. of Chemical and Biochemical Engineering, Pusan National University)
  • Received : 2009.04.30
  • Accepted : 2009.07.18
  • Published : 2009.08.31

Abstract

A polymer composite electrolyte of a blend of poly(methyl methacrylate)(PMMA) and poly(ethylene oxide) (PEO) as a host polymer, the ethylene carbonate as a solvent, and $LiClO_4$ as a salt was studied. The crystallinity of the polymer electrolytes was evaluated using differential scanning calorimeter(DSC). The ionic conductivity of the polymer electrolytes was measured by frequency response analyzer(FRA) method. The effect of PEO/PMMA blend ratios on the ionic conduction in these electrolytes was investigated. The electrolyte films showed a phase separation due to immiscibility of the PMMA with the PEO. The PMMA-rich phase and the PEO-rich phase were produced during a film casting. The ionic conductivity of blend electrolyte was dependent on the content of PMMA and showed the highest value at 20 wt.%. However, when PMMA content exceeds 20 wt.%, the ionic conductivity was decreased due to the slow ionic transport through the PMMA-rich phase.

본 연구는 리튬 이차전지용 고분자 전해질 복합재료에 관한 것으로, 고분자는 poly(ethylene oxide)(PEO)와 poly(methyl methacrylate) (PMMA) 블렌드를 사용하고, 용매로는 Ethylene carbonate(EC), 그리고 $LiClO_4$를 리튬염으로 하는 전해질 복합체 필름을 제조하였으며, PMMA의 함유량에 따른 고분자 전해질의 전기화학적 특성을 관찰하였다. 제조된 고분자 전해질의 결정화도와 이온전도도는 시차주사열량계(DSC)와 주파수반응분석기(FRA)로 분석하였다. 그 결과 PMMA의 함량을 증가시킴에 따라서, PEO의 결정 영역이 감소하고 이온전도도가 증가하였다. 또한, PMMA의 함량이 20 wt.% 이상인 경우, 고분자 블렌드필름에서 상분리되는 현상을 관찰하였다. 즉, SEM 분석결과에 의해서, PMMA 주성분 영역과 PEO 주성분 영역의 구분이 가능하였다. 고분자 전해질의 이온전도도는 20 wt.% 첨가한 경우 가장 큰 이온전도도를 가지며, 함유량이 20 wt.% 이상에서는 PMMA 상의 증가로 인해 다소 감소된 이온전도도 변화를 나타내었다.

Keywords

Acknowledgement

Supported by : 부산대학교

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