Exploring Ionic Motion and Conductivity Enhancement in PEO:NaI:MnO₂ Polymer Electrolytes with DEC Plasticizer

This study investigates the effect of diethyl carbonate (DEC) plasticizers on ionic conductivity. Additionally, the research investigated the mobility and concentration of charge carriers in (PEO:NaI:MnO₂) + DEC wt% polymer electrolytes using theoretical models (Trukhan and Schutt & Gerdes models). Here, the thin films were synthesised using solution casting techniques with varying DEC concentrations (0–100 wt%) and characterised using impedance spectroscopy. The results indicate that ionic conductivity greatly depends on the amount of DEC, and we got the highest conductivity of 8.72 x 10 − 4 S/cm at 60 wt% of DEC. This increase in conductivity is expected due to an increase in amorphous nature, ion separation, and the formation of a percolation pathway that offers improved ion transport. At the higher concentration of DEC, conductivity declined due to phase separation and dilution effects. To gain a more profound understanding of how ions move with frequency, the Distribution of Relaxation Times (DRT) for the 60 wt% DEC was calculated. This calculation was performed under a temperature-dependent environment and reveals that relaxation time (τ) is inversely proportional to the rate of a process. A shorter time constant means a faster process, which offers the higher conductivity. Additional studies that looked at temperature effects confirmed Arrhenius-type behavior and found an activation energy of 0.51 eV. Charge carrier and concentrations analysis using the Trukhan and Schutt & Gerdes models showed that the Trukhan model provided a more accurate description of ion transport in the amorphous matrix compared to the Schutt & Gerdes model. The findings of this study demonstrate that optimizing plasticizer concentration is critical for achieving high-performance polymer electrolytes, which is helpful in the design of next-generation energy storage devices.