가교된 폴리비닐 알콜계 화합물을 이용한 리튬 2차전지용 고분자막 합성 및 특성연구

Abstract

The carbonate group was introduced into the polymeric gel electrolyte to enhance the compatability with EC/DEC without losing ion conductivity which were widely used in lithium ion battery as liquid electrolyte . The poly(vinyl alcohol)(PVA) was modified by reacting with dimethyl carbonate in the presence of tetrabutyl ammonium bromide as a catalyst. The carbonate group can be introduced as mono-carbonate by reacting with one hydroxyl group, cyclic-carbonate by reacting with two adjacent hydroxyl group in PVA chain or crosslinked structure through the inter chain reaction. The PVA carbonates(PVAC) was further crosslinked with poly(ethylene glycol)(PEG) which has lithium ion transporting ability through the ion-dipol interaction and segmental motion of flexible structure. Both mono-carbonate and cyclic-carbonate structure increased with DMC content. Thermal property of the PVAC-co-PEG showed high thermal stability up to 200℃, and there is no evidence that the PVAC-co-PEG is crystalline. AC impedance and ion conductivity decreased with increasing DMC content. On the other hand, they increased with increasing PEG content. The maximum ion conductivity obtained is 2.1 x 10-3 S/cm at room temperature.