Theory of Melting Point Depression for Polymer Blend(PEO-PPO) Electrolyte /LiCF3SO3 Systems in Lithium Battery

Abstract

Polymer blend (Poly(ethylene oxide)(PEO)-poly(propylene oxide)(PPO)) systems with two different mole ratios, complexed with LiCF3SO3 salt, have been characterized at various temperatures and compositions by thermo-optical analysis(TOA) technique. We also develop a new melting point depression theory based on the modified perturbed hard sphere chain (PHSC) model to interpret phase behaviors of polymer blend electrolyte systems. The obtained results show that the eutectic points move toward higher Tm and lower weight fraction of salt with decreasing PEO mole ratio, and also indicates that the mole ratio of PEO:PPO for each polymer blend plays an important role in determining the eutectic point of the polymer blend system.