Electrospun electroactive polyvinylidene fluoride-based fibrous polymer electrolyte for sodium ion batteries

Abstract

Electrospinning is an efficient technique to produce ultrafine electroactive mat, diameters ranging from few nanometers to micrometers to use as a separator in sodium ion battery. The polyvinylidene fluoride (PVDF) polymer solution was optimized to 19 wt%, applied voltage 25 kV and flow rate of 0.5 ml h-1 to get a bead free ultrafine electroactive structure. The electroactive ?-phase is confirmed by x-ray diffractometer (XRD). Ionic conductivities, electrolyte uptake, wettability, linear sweep voltammetry (LSV) and thermal stability of the electroactive fibrous polymer electrolyte (EFPE) were studied by soaking the separator with a liquid electrolyte of 1 M sodium hexafluorophosphate (NaPF<inf>6</inf>) dissolved in ethylene carbonate (EC)/propylene carbonate (PC) (1:1 vol%). The EFPE exhibits high ionic conductivity of 1.08 mS cm-1 and electrochemical stability window of 5.0 V versus Na/Na+ under ambient condition. The half-cell containing Na<inf>0.66</inf>Fe<inf>0.5</inf>Mn<inf>0.5</inf>O<inf>2</inf> as cathode and EFPE as the separator cum electrolyte showed a stable cycling performance at a current rate of 0.1C. © 2019 IOP Publishing Ltd.