Impact of Glass Particles on Sodium-Ion Conducting Solid Polymer Electrolytes

Solid-state electrolytes are promising candidates to replace conventional liquid/aqueous electrolytes, which offer enhanced safety, mechanical integrity, flexibility, and better electrochemical performance. In the present study, a novel composite system has been developed by dispersing NB13 (1Na₂O:3B₂O₃) sodium borate glass powder into a poly (ethylene oxide) (PEO)-based solid polymer electrolyte (SPE) matrix: [70 PEO:30(50NaI + 50Na₃PO₄)] [1]. The NB13 glass was synthesized using the popular melt-quench method, ground into powder by mechanical ball milling and dispersed into the PEO-based SPE host matrix as the 2nd-phase dispersoid. Uniform, flexible, thin glass-composite polymer electrolyte (GCPE) films were synthesized using the hot-press method. The electrical, dielectric, and electrochemical properties of the novel composite membranes were investigated at room temperature using a precision LCR meter and cyclic voltammetry (CV) with symmetrical cells “SS||GCPE/SPE||SS” (SS stainless steel). X-ray diffraction (XRD) analysis confirms the amorphous nature of the NB13 glass powder and its complexation with the salt and polymer matrix, while differential scanning calorimetry (DSC) analysis revealed a significant reduction in crystallinity. The optimum conducting composition (OCC) of the GCPE film exhibited an enhancement of one order of magnitude in ionic conductivity at room temperature compared to the SPE host. The GCPE films demonstrated a stable electrochemical operating window of − 3.0 to 3.0 V, excellent electrochemical stability over 10 cycles, high ionic conductivity (~ 10⁻⁵ S/cm) at room temperature, low activation energy (E_a ~ 0.24 eV), and ionic transference number which is close to unity (~ 1). These results suggest the GCPE system is a potential candidate for solid-state battery applications.