Enhanced ionic conductivity in NaPF6-based PEO/PVDF-HFP nanocomposite plasticized polymer electrolytes: Effect of Al2O3 nanofiller

Nanocomposite plasticized polymer electrolytes (NCPPEs) are new materials that are great for energy storage devices because they have excellent ionic conductivity, are strong enough to withstand stress, and are stable at high temperatures. This study examines the synthesis, structural characterization, and electrochemical performance of NCPPEs by incorporating nano-filler aluminium oxide (Al 2 O 3 ) and the plasticizer ethylene carbonate (EC) into polymer blend matrices of poly (ethylene oxide) (PEO) and poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) complexed with sodium hexafluorophosphate (NaPF 6 ). While plasticizer EC reduces polymer crystallinity, increasing ion mobility, the addition of nanofiller Al 2 O 3 improves ionic transport channels and mechanical strength through extensive interfacial contacts. NCPPEs are synthesized using solution casting method according to the weight ratios such as 70 wt%PEO: 30 wt%PVDF-HFP+7 wt% NaPF 6 +8 wt%EC+x wt%Al 2 O 3 (where x = 0.5, 1, 1.5, 2 and 2.5). Structural characterization studies like X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed optimized Nano-filler distribution, and reduced crystallinity. FTIR analysis showed that, due to the coordination of Na + and the introduction of Al 2 O 3 , strong ion-polymer interactions, reduced PEO crystallinity, and structural rearrangement occurred within the polymer matrix. DSC analysis showed that the NCPPE membrane containing 2 wt%Al 2 O 3 had the lowest melting temperature and the highest amorphous state. Electrochemical impedance spectroscopy (EIS) demonstrated significant enhancements in ionic conductivity. From the key findings it can be observed that NCPPE film with 2 wt%Al 2 O 3 has the highest ionic conductivity of 0.33 × 10 −3 S/cm and lowest activation energy of 0.107 eV which is attributed to the optimized Nano-filler distribution, and reduced crystallinity. Hence, 70 wt%PEO:30 wt%PVDF-HFP+7 wt%NaPF 6 +8 wt%EC+ 2 wt%Al 2 O 3 is the optimization ratio in the current study and suitable for practical applications in sodium-ion batteries as electrolyte material.