Role of TiO2 nanofiller in modulating ionic conduction and dielectric behaviour of PVA/NaClO4 polymer electrolyte

Solid polymer electrolytes (SPEs) are attractive alternatives to liquid electrolytes owing to their improved safety, flexibility and ease of processing. Titanium dioxide (TiO 2 ) is an attractive nanofiller for SPEs because of its high dielectric constant, chemical stability and ability to promote polymer-ion interactions that facilitate ionic transport. Although TiO 2 has been incorporated into PVA based polymer electrolytes, a systematic understanding of its influence on the combined structural, dielectric, electrochemical and mechanical properties remain limited. In this work, PVA/NaClO 4 /TiO 2 nanocomposite polymer electrolytes were prepared by a solution casting technique to establish these structure–property relationships. X-ray diffraction and ATR-FTIR analyses confirmed structural modification and interactions among the polymer matrix, Na⁺ ions and TiO 2 nanoparticles. The optimized electrolyte containing 3 wt% TiO 2 exhibited the highest ionic conductivity of 4.43 × 10 −5 S cm −1 , an ionic transference number of 0.99, and an electrochemical stability window of 3.2 V. Dielectric analysis revealed enhanced relaxation behaviour with a minimum relaxation time of 3.89 μs, while FE-SEM and mechanical studies confirmed uniform nanofiller dispersion and adequate film integrity. Overall, the results demonstrate that optimizing TiO 2 content enables a balanced improvement in ionic transport, dielectric response, electrochemical stability and mechanical performance, providing useful insights for developing PVA-based solid polymer electrolytes for future sodium-ion energy storage applications.