PEO/P(VdF-HFP) blend based Li+ ion-conducting composite polymer electrolytes dispersed with dedoped (insulating) polyaniline nanofibers

Composite polymer electrolyte membranes composed of poly(ethylene oxide) (PEO), poly(vinylidene fluoride-hexafluoropropylene) {P(VdF-HFP)} blends, dedoped (insulating) polyaniline (PAni) nanofibers, and LiClO4 as salt have been synthesized with varying fraction of dedoped PAni nanofibers (from 2 to 10 wt.%). The ionic conductivity of PEO-P(VdF-HFP)-LiClO4 electrolyte system increases with increase in the fraction of dedoped polyaniline nanofibers. This could be attributed to the incorporation of nanofibers (aspect ratio > 50), which may provide high ion conducting path along the interface due to Lewis acid-base interactions between Li+ ions and lone pair of electrons of nitrogen atom of polyaniline. However, at higher fraction (> 6 wt.%), the nanofibers get phase separated from the polymer matrix and form domain-like structures, which may act as physical barrier to the conduction of Li+ ions resulting in decreased ionic conductivity. Electrochemical potential window and interfacial stability of nanofibers dispersed polymer electrolyte membranes are also better than that of nanofibers free membranes.