Enhancing lithium-ion conductivity: impact of hausmannite nanofiller on PVDF–HFP/PEG blend nanocomposite polymer electrolytes

Abstract

A new series of PVDF–HFP/PEG-based nanocomposite polymer electrolytes (NCPEs) have been fabricated using hausmannite (Mn₃O₄) nanoparticles as the nanofiller and LiClO₄ as the lithium-ion source via the solvent casting method. A pristine PVDF–HFP NCPE sample with 2 wt% nanofiller was also prepared for comparison. The Mn₃O₄ nanoparticles were synthesized by the precipitation method using CTAB as a templating agent and MnCl₂·4H₂O as the precursor. FTIR spectroscopy showed that while pristine PVDF–HFP forms a nonpolar α-phase, the incorporation of salt and nanofiller induced a mixed β and γ crystal phase, indicating interaction between the matrix and additives. Surface morphology studies showed that the NCPEs had a denser surface than pristine PVDF–HFP, with no PEG spherulite formation detected in polarized optical micrographs. Electrochemical impedance spectroscopy revealed that the 2% blend NCPE exhibited the highest ion conductivity of 3.1 × 10⁻⁴ S cm⁻¹ at 80 °C, an order of magnitude higher than the pristine NCPE (5.1 × 10⁻⁵ S cm⁻¹). Temperature-dependent ion conductivity followed Arrhenius behavior, indicating a thermally activated ion hopping mechanism. The dielectric relaxation peak shifted to higher frequency with increasing temperature, suggesting faster ion dynamics and improved conductivity.