Influence of Germanium oxide nanoparticles on the electrical conductivity of Li-ion conducting NaCMC/PVA nanocomposite films

This study examines the influence of GeO₂ nanoparticles (NPs) on the ionic conductivity and structural properties of NaCMC/PVA/LiBr-based solid polymer electrolytes synthesized via solution casting technique. XRD analysis revealed enhanced amorphous character with increasing GeO₂ content. FTIR spectra confirmed interactions between GeO₂ NPs and the polymer-salt matrix. SEM and EDX analyses were used to investigate morphology and elemental composition. UV–Vis spectroscopy showed a redshift in absorption edge and a bandgap reduction from 5.70 to 5.50 eV with GeO₂ addition. Impedance spectroscopy (100 Hz - 5 MHz) indicated improved ionic conductivity, following Jonscher's universal power law, with a maximum value of (1.13 ± 0.02) × 10⁻⁵ S cm⁻¹ at 5 wt% GeO₂. LSV confirmed electrochemical stability up to 2.7 V. Dielectric studies revealed an increase in permittivity due to interfacial polarization. Transference number measurement evaluates the relative contributions of ionic and electronic charge carriers in solid polymer electrolytes using polarization technique. These results highlight the potential of GeO₂-dispersed NaCMC/PVA/LiBr films for energy storage applications.