Polymer composite electrolyte of SPSU(Na)/PPEGMA/hBN for sodium-ion batteries

Polymer composite electrolyte based on polysulfone-sodium sulfonate (SPSU(Na)) blended with poly (polyethylene glycol methacrylate) (PPEGMA) using nano-sized hexagonal boron nitride (nano-hBN) as filler was fabricated using a solution casting technique for use in Na-ion batteries. Polysulfone was sulfonated by a post sulfonation method followed by ion exchange with sodium hydroxide. Fourier transform infrared spectroscopy was used to study SPSU(Na)/PEGMA blend and incorporation of hBN nanoparticle into the SPSU(Na)/PPEGMA blend. Thermal properties of the composites were studied with thermogravimetric analysis (TGA) and differential scanning calorimetry tests. X-ray diffraction was used to study phase change. The TGA curve showed two weight loss regions, where 30% weight loss occurred between 200°C and 350°C due to degradation of sulfonic acid groups, and the polymer backbone degradation occurs above 500°C. Surface morphology of the membranes was examined using scanning electron microscopy which reveals the homogeneous dispersion of the nano-hBN particles in the polymer matrix. Ionic conductivity was studied with impedance spectroscopy and the total ionic conductivity increases with increasing PPEGMA ratio. SPSU(Na)/PPEGMA(1:4) sample showed maximum ion conductivity of approximately 5.5 × 10 ⁻⁶ S cm ⁻¹ (5.5 × 10 ⁻⁴ S m ⁻¹ ) at 100°C because of the high content of PPEGMA.