Conductivity and Morphology of Hybrid Electrolytes based on Blends of Pvdf With PEO-co-PPO Copolymers

摘要

Hybrid film elelctrolytes with high room temperature conductivity have been prepared by casting solutions of PVDF-HFP copolymers with PEO-PPO block copolymers and PEO oligomers followed by activation of the polymer blend films in electrolyte solutions. The morphology and conductivity of these solid electrolytes were studied as a function of concentration, and conductivity of these slid electrolytes were studied as a function of concentration, molecular weight and sequence order of the PEO and PEO-PPO copolymers, and also of the casting solvent and evaporation rate of the casting solvent. Structural studies of PVDF-HFP/PEO and PVDF-HFP/PPO-co-PEO blend films before activation with lithium salt electrolyte may indicate the occurrence of spinodal decomposition in the films during slow evaporation of the casting slovent. As a result of spinodal decomposition, an interpenetrating bi-continuous phase may evolve with microphase separation between PVDF-HFP and PPO-PEO phases, in which the PVDF phase provides mechanical support and the PPO-PEo phase provides a conductive path.