Na₃Zr₂Si₂PO₁₂-Polymer Composite Electrolyte for Solid State Sodium Batteries

The integration of the flexibility of organic polymer electrolyte and high ionic conductivity of the ceramic electrolyte is attempted in search of efficient and safer battery. Composite solid polymer electrolyte (CSPE) provides high ionic conductivity with a sustainable thin film of electrolyte having the synergistic effect of ionic liquid and active inorganic filler. The CSPE is synthesized by the solution cast technique using Na₃Zr₂Si₂PO₁₂ (NZSP) as ceramic and poly(vinylidene fluoride-hexafluoropropylene) with Salt-Ionic liquid as polymer electrolyte. X-ray diffraction (XRD) of CSPE includes amorphous nature due to the polymer part as well as crystalline peaks of ceramic NZSP, simultaneously. The prepared CSPE sample shows homogeneous and interconnected surface morphology is observed by Scanning electron microscopy (SEM) image. Thermogravimetric analysis (TGA) shows electrolyte is thermally stable up to 200 °C and differential scanning calorimetry (DSC) reveals decrease in degree of crystallinity due to NZSP addition in the CSPE. By complex impedance spectroscopy (CIS), room temperature ionic conductivity of the prepared CSPE is found ~1.03 mS/cm. The dielectric behaviour of the prepared electrolyte is also studied to investigate the ion dynamics within the sample. The cationic transference number is 0.53 and the electrochemical stability window (ESW) of the CSPE is 4.9 V which is suitable for sodium solid-state batteries applications.