Graft copolymer electrolytes for electrochemical double layer electrochemical capacitor applications

Abstract

In this study, a new type of graft copolymer based on polyethylene glycol monomethyl ether (PEGME) grafted poly(vinyl alcohol-co-acrylonitrile) (poly(VA-co-AN)) was produced. The synthesis of the copolymer was certified by spectroscopic techniques, and then the gel polymer electrolytes (GPEs) were acquired by doping with LiBF4 at various mass ratios. The polymer electrolytes indicated promising thermal stabilities up to 220 °C and obtained amorphous nature after grafting. Moreover, the insertion of PEGME side chains softened the materials and improved the ionic conductivity. The polymer electrolyte, PE (poly(VA-co-AN)/PEGME/XH3BO3/YLiBF4 X, Y; 10, 5 in moles), illustrated high conductivity at ambient temperature. The electrochemical capacitor device fabricated with GPE3 electrolyte yielded a specific capacitance of 105 F g−1 at a specific current of 1 A g−1. The specific density of 14.8 Wh kg−1 was obtained from the same device at a specific power of 5000 W kg−1. Excellent cyclic stability with a high coulombic efficiency of 90% was observed after 30 days of consecutive measurements at a specific current of 1 mA g−1.