Poly(vinylidene fluoride)–polydiphenylamine composite electrospun membrane as high-performance polymer electrolyte for lithium batteries

Abstract

Composites of poly(vinylidene fluoride) (PVdF)–polydiphenylamine (PDPA) are electrospun as nanofibrous membranes, PVdF–PDPA-CFM (CFM represents composite nanofibrous membrane). Polymer electrolytes are prepared by loading lithium salts into PVdF–PDPA-CFM. Field emission scanning electron microscope (FESEM) images clearly inform that PVdF–PDPA-CFM has interconnected multi-fibrous layers with ultrafine porous structures. The average diameter of fibers in PVdF–PDPA-CFM is ∼200 nm for a loading of 0.5 wt.% of PDPA in the composite, which is far lesser than pristine PVdF membrane. There is inter-fiber twisting in the PVdF–PDPA-CFM that generates microcavities. These interconnected morphological features of PVdF–PDPA-CFM result in higher ionic conductivity, effective lithium ion transport and good interfacial characteristics with lithium electrode. Higher ionic conductivity, lithium ion transport number of about 0.48, higher liquid electrolyte uptake (>280%) with dimensional stability, lower interfacial resistance and higher electrochemical stability window of 5.18 V vs. Li for PVdF–PDPA-CFM electrolyte are witnessed. With these improved performance characteristics, PVdF–PDPA-CFM finds its suitability as polymer electrolyte for high-performance lithium rechargeable batteries.