| 초록 |
Common solvent-free solid polymer electrolytes(SPEs) are not entirely free from the drawback of lower ionic conductivity than gel polymer electrolytes(GPEs). To overcome this defect, we have prepared SPEs based on poly(vinyl alcohol)(PVA) containing the salt of lithium triflate(LiCF3SO3, LiTf). PVA has high glass transition temperature(Tg) and good mechanical properties. And despite being atactic, PVA can crystallize, especially if highly hydrolyzed, since the hydroxyl group can be accommodated in place of a hydrogen atom in the crystal lattice of polyethylene. For these reasons, it can be used to observe the change of the crystallinity with different salt concentrations and decoupled ion transportation. Namely, PVA is suitable to use as the matrix for new type SPEs. Several techniques, such as ac impedance, FTIR spectroscopic measurement, XRD and AFM were applied to characterize the samples. In results, we found that the ionic conductivity increased with increasing salt concentration. Especially, the ion conductivity increased dramatically between 40 and 50wt% of salt concentration. Through FTIR spectra, we could analyze the change of salt forms in various salt concentrations. In XRD patterns, we could observe the change of the crystallinity of the samples and we could survey the surface of SPEs by using AFM. The highest ionic conductivity of our SPEs was 1.42ⅹ10-3S/cm with 80wt% of salt concentration at room temperature. |
