UV cured polymer electrolytes were prepared from poly(ethylene glycol) ethyl ether methacrylate. poly(ethylene glycol)diacrylate, lithium salts, and propylene carbonate and ethylene carbonate were used as plasticizers. The ionic conductivity of the polymer electrolytes was increased with the amount of the plasticizers but optimum content of the plasticizers was about 55 wt% based on the weight of the polymer in the consideration of their mechanical property. The highest ionic conductivity was 1.9 x 10^-3S/cm when the mol ratio of ethylene oxide repeating unit to Li⁺ was 10. It was found that the temperature dependency of the ionic conductivity followed Vogel-Tamman-Fulcher equation, which indicates that the segmental motion of the polymer chains acts as an important role in transportation of Li ion. The ionic conductivity was varied with the kinds of lithium salts in the range of 10^-3∼10^-4S/cm. The polymer electrolyte with lower crosslinking density had more phase-separated structure and showed higher ionic conductivity comparing with the polymer electrolyte with higher crosslinking density. From the result of linear sweep voltammetry, the polymer electrolytes were shown to be electrochemically stable up to 4.9 V.

Poly(ethylene glycol) ethyl ether methacrylate, poly(ethylene glycol)diacrylate, lithium salts 및 가소제로서 propylene carbonate와 ethylene carbonate를 사용하여 자외선경화된 고분자전해질을 제조하였다. 고분자전해질의 이온전도도는 가소제의 양에 비례하여 증가하였으나 기계적 물성을 고려할 때 고분자에 대해 55 wt%정도가 최적이었다. 가소제 함량 및 ethylene oxide 반복단위에 대한 리튬이온의 몰비가 10일 때 이온전도도가 가장 높았으며 그 값은 1.9 x 10^-3S/cm이었다. 자외선경화된 고분자전해질의 이온전도도는 vogel-Tamman-Fulcher equation에 따르는 온도의존성을 나타내었는데, 이는 고분자의 분절운동이 리튬이온의 이동에 중요한 역할을 한다는 것을 뜻한다. 사용된 리튬염의 종류에 따라 이온전도도는 10^-3∼10^-4S/cm 범위에서 다소 차이를 보였다. 가교밀도가 낮을수록 이온전도도가 높았으며 낮은 가교밀도의 고분자전해질이 높은 가교밀도의 고분자전해질에 비해 보다 상분리린 구소를 나타내었다. Linear sweep voltammetry 실험결과 고분자전해질은 4.9 V까지 전기화학적으로 안정하였다.

Keywords: polymer electrolyte; crosslinking density; ionic conductivity; VTF equation; linear sweep voltammetry