High-performance poly(vinylidene fluoride-co-hexafluoropropylene) based electrospun polyelectrolyte mat for lithium-ion battery

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer was modified by chemical treatments to obtain functionalized material for the preparation of electrolytes suitable for application in Lithium polymer battery. The PVdF-HFP was chemically modified by dehydrofluorination/sulphonation, reaction with acrylate and also by grafting of tertiary butyl acrylamide using atom transfer radical polymerization (ATRP). The PVdF-HFP modified by various chemical treatments was elecrospun into fibrous mat and also cast into films. Polyelectrolytes were prepared by introducing lithium ions into the nanofibrous mat and films of modified PVdF-HFP. The chemical modification occurred on PVdF-HFP was confirmed by fourier transform infrared spectroscopic (FTIR) analysis. The ionic conductivity, thermal stability, morphological characteristics of electrospun nanofibers and films prepared from both unmodified and chemically modified PVdF-HFP were investigated using electrochemical impedance spectroscopy (EIS), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) respectively. The electrolytes produced in the form of nanofibers possess improved thermal stability and ionic conductivity due to the presence of micropores. The ionic conductivity of the chemically modified PVdF-HFP electrospun nanofibrous electrolyte was observed in the range of 1.09 x 10(-3) Scm(-1), which is greater than the ionic conductivity of chemically modified PVdF-HFP films. This is due to the large surface area and porous structure of the nanofibrous mat which facilitate the uptake of large amount of liquid electrolyte. The chemically modified PVdF-HFP nanofibrous electrolyte developed in the present work would be a promising candidate for enhancing the performance of Lithium batteries.