Ionic Transport Enhancement in Sodium Salt-Modified Graphene Oxide Solid Electrolytes

Graphene oxide (GO)-based solid electrolytes offer a safer and more stable alternative to conventional liquid electrolytes for energy storage systems. This study examines the influence of sodium salt incorporation specifically sodium sulfite, sodium nitrate, and sodium chloride on the characteristic, thermal, and ionic transport properties of GO-based solid electrolytes. The solid electrolyte membranes were fabricated using the vacuum filtration method. X-ray Diffraction (XRD) analysis revealed an increase in the interlayer spacing of GO nanosheet after the addition of sodium salts. Fourier Transform Infrared Spectroscopy (FTIR) results indicated the occurrence of ring opening or the cleavage of C-O-C bonds into C-O-H bonds, suggesting enhanced oxidation through the conversion of epoxy groups into carbonyl groups. Scanning Electron Microscopy (SEM) images showed that the addition of sodium salts widened the interlayer spacing. Thermal analysis using Thermogravimetric Analysis (TGA) demonstrated that the membranes exhibited lower mass loss at each stage after the addition of sodium salts, indicating improved thermal stability compared to those without sodium salts. Electrochemical Impedance Spectroscopy (EIS) results confirmed an increase in ionic conductivity of GO-based solid electrolytes following sodium salt incorporation, with the highest conductivity of 4.07 × 10^-4 S/cm observed for GO-NaCl at room temperature with a 20 wt. concentration. These results demonstrate that controlled sodium salt modification promotes favorable ion-GO interactions, thereby enhancing ionic transport and improving the performance potential of GO-based solid electrolytes for energy storage applications.