Enhancing the properties of PEG-based solid polymer electrolytes with TiO2 nanoparticles for potassium ion batteries

In this study, nanocomposite solid polymer electrolytes (NSPEs) based on poly(ethylene glycol) (PEG), potassium nitrate (KNO₃), and titanium oxide (TiO₂) nanoparticles were synthesized using a solution casting technique. The impact of various TiO₂ nanoparticle concentrations on the structural, thermal, electrical and electrochemical properties of the NSPEs was investigated. X-ray diffraction analysis revealed a decrease in the degree of crystallinity of the PEG–KNO₃ electrolyte upon the addition of TiO₂ nanoparticles. Differential scanning calorimetry measurements showed a decrease in the melting temperature of the NSPE with the incorporation of 6 wt.% TiO₂ nanoparticle concentration. The ionic conductivity of the NSPEs increased with TiO₂ concentration up to 6 wt.% (σ = 5.94 × 10⁻⁵ S/cm), beyond which a decrease was observed. Transference number measurements confirmed the dominance of ionic charge transport in the NSPE. A solid-state electrochemical cell fabricated using the optimal NSPE composition (80PEG–20KNO₃–6 wt.% TiO₂) exhibited promising discharge performance under a constant load of 100 kΩ.