Polymer electrolytes based on poly(vinylidenefluoride-hexafluoropropylene) and cyanoresin

Abstract

Lithium gel electrolytes based on a mixed polymer matrix consisting of poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP) and cyanoresin type M (CRM) were prepared using an in situ blending process. The CRM used in this study was a copolymer of cyanoethyl pullulan and cyanoethyl poly(vinyl alcohol) (PVA) with a mole ratio of 1: 1. The mixed plasticizer was ethylene carbonate (EC) and propylene carbonate (PC) with a volume ratio of 1: 1. In this study, the presence of PVDF in the electrolytes helps to form a dimensionally stable film over a broad composition range, and decreases the viscosity. In addition, it provides better rheological properties that are suitable for the extrusion of thin films. However, the presence of HFP has a positive effect on generating an amorphous domain in a crystalline PVDF structure. The ionic conductivity of the polymer electrolytes was investigated in the range 298-333 K. The introduction of CRM into the PVDF-HFP/LiPF6 complex produced a PVDF-HFP/CRM/LiPF6 complex with a higher ionic conductivity and improved thermal stability and dynamic mechanical properties than a simple PVDF-HFP/LiPF6 complex.