Nanofiber membrane based on ionic liquids as high-performance polymer electrolyte for sodium electrochemical device

Composite nanofibrous electrolyte membranes (CFEM) of poly(vinylidene fluoride-hexafluoropropylene) P(VdF-HFP)-1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄) and its NaSCN are electrospun as nanofibrous membranes. Scanning electron microscope (SEM) images clearly inform that electrospun CFEM and CFEM–NaSCN with average fiber diameters of 50–200 nm have interconnected multifibrous layers with ultrafine porous structures. They exhibited a high uptake of the electrolyte solution (370–880 %). The polymer electrolytes have decreased crystalline, which is advantage to the increase in ionic conductivity. In addition, polymer electrolytes also are prepared by swelling nanofibre into blend of sodium salt and BMIMBF₄. CFEM obtained 15 % BMIMBF₄ exhibited higher ionic conductivity maximum of 5.6?×?10^?5 S cm^?1 at room temperature, and the conductive model of CFEM–NaSCN electrolyte answer for Arrhenius function. CFEM–NaSCN electrolyte showed a high electrochemical window of above 4.5 V, which is higher than electrospun pure P(VdF-HFP) without BMIMBF₄ or BMIMBF₄–NaSCN. With these improved performance characteristics, CFEM electrolyte and CFEM–NaSCN electrolyte will be found its suitability as polymer electrolyte for high-performance rechargeable batteries and super capacitor.