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

• Developed nanocomposite solid polymer electrolyte using solution casting method. • The composites show an ionic conductivity as high as 5.94 × 10 −5 S/cm at 30 °C. • XRD and DSC analysis confirmed a reduction in crystallinity. • Nanocomposite solid polymer electrolyte exhibits a high ion transport number. • Better battery performance obtained for 80PEG-20KNO 3 –6 wt.% TiO 2 electrolyte. In this study, nanocomposite solid polymer electrolytes (NSPEs) based on poly(ethylene glycol) (PEG), potassium nitrate (KNO 3 ), and titanium oxide (TiO 2 ) nanoparticles were synthesized using a solution casting technique. The impact of various TiO 2 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–KNO 3 electrolyte upon the addition of TiO 2 nanoparticles. Differential scanning calorimetry measurements showed a decrease in the melting temperature of the NSPE with the incorporation of 6 wt.% TiO 2 nanoparticle concentration. The ionic conductivity of the NSPEs increased with TiO 2 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–20KNO 3 –6 wt.% TiO 2 ) exhibited promising discharge performance under a constant load of 100 kΩ.