| 초록 |
We develop a new melting point depression theory based on the extended perturbed-hard-sphere-chain(PHSC) model that takes into account the local composition concept for solid polymer electrolyte(SPE)/salt systems in Lithium Secondary battery. While manufacturing SPE, salts are localized partly in the whole system. Ion conductivity of the system, therefore, is seriously affected. Our previous work of SPE/salts system do not consider the nonrandomness effect for the ion conductivity. In this study, to take into account nonrandom distribution of salts in SPE, we introduce the nonrandomness contribution in the perturbation term containing specific interactions between polymer molecules and salts. We use the nonrandom distribution function in the perturbation term derived by Sadowski instead of using the traditional van der Waals expression. Systems used in this study are PEO/zinc halide (e.g. ZnCl2, ZnBr2 and ZnI2) and PEO/LiCF3SO3. In comparison with experimental data, quantitative descriptions of the proposed model show better agreement for the given systems than those of the previous works. The obtained results show that the nonrandomness effect of salt distribution as well as the effects of the salt weight fraction and the size of salt molecule plays a great role in determining eutectic points of the given systems. |
