Ionic Conductivity, Na Plating–Stripping, and Battery Performance of Solid Polymer Na Ion Electrolyte Based on Poly(vinylidene fluoride) and Poly(vinyl pyrrolidone)
Afshana Afroj Bristi, Alfred Junio Samson, Abinaya Sivakumaran, Shantel Butler, Venkataraman Thangadurai
Abstract
Solid-state sodium-ion batteries (ss-SIBs) are a promising alternative to commercially available lithium-ion batteries for next-generation energy storage applications due to the abundance and cost-effectiveness of sodium over lithium. Herein, using a facile solution casting process, a high sodium-ion conductive, filler-less composite solid polymer electrolyte (SPE) film based on poly(vinylidene fluoride) polymer, poly(vinyl pyrrolidone) (PVP) binder, and NaPF6 salt for ss-SIB has been successfully fabricated. Total conductivities of 8.51 × 10–4 and 8.36 × 10–3 S cm–1 at 23 and 83 °C, respectively, were observed from the SPE. A hybrid symmetric half-cell assembly using Na electrode and 1 M NaClO4 in ethylene carbonate (EC) and propylene carbonate (PC) (EC/PC = 1:1 wt %) electrolyte showed excellent Na plating–stripping performance at 10 mA cm–2 at 23 °C. The study showed that PVP binder played an important role in achieving good Na ion conductivity and excellent Na plating–stripping performance, highlighting the applicability of the as-prepared SPE in next-generation high-power rechargeable SIBs. A full cell with an SPE, a Na anode, and a Na3V2(PO4)3 cathode showed a discharge capacity of 93.2 mAh g–1 at 0.1 C with 86% capacity retention and 99.68% Coulombic efficiency for 100 cycles.