Enhancing ionic conductivity, mechanical stability and electrochemical properties simultaneously by integrating POSS-PEG13.3 hybrid nanoparticles into PEO-NaClO4 solid polymer electrolytes

The increasing global energy demand and environmental concerns necessitate the development of sustainable energy storage solutions. Sodium-ion batteries have emerged as a promising alternative to lithium-ion batteries due to the abundance and low cost of sodium. This study investigates the impact of incorporating hybrid nanoparticles, specifically polyhedral oligomeric silsesquioxane - poly(ethylene glycol) (POSS-PEG_13.3), on the performance of polyethylene oxide (PEO) - sodium perchlorate (NaClO₄) based solid polymer electrolytes (SPEs). The results demonstrate that the incorporation of POSS-PEG_13.3 effectively disrupts the crystallinity of the PEO matrix, as confirmed by X-ray diffraction and differential scanning calorimetry analyses. Consequently, the ionic conductivity of the SPEs increases with increasing POSS-PEG_13.3 content, reaching a maximum of 1.02 × 10^–4 S/cm at 30 °C for the electrolyte containing 40 wt.% of POSS-PEG_13.3. Furthermore, the addition of POSS-PEG_13.3 significantly improves the mechanical properties of the SPEs, enhancing their stability and durability. The ionic transference number (t_ion = 0.988) confirm that ions are the primary charge carriers in these electrolytes. Additionally, linear sweep voltammetry and battery discharge studies indicate a wide electrochemical stability window of 3.32 V, demonstrating the suitability of these SPEs for Na-ion battery applications.