Sodium‐Ion Conducting Tamarind Seed Polysaccharide‐NaBF ₄ Solid Biopolymer Electrolytes: Ionic Conductivity and Electrochemical Performance

ABSTRACT In this work, tamarind seed polysaccharide (TSP)‐based solid biopolymer electrolytes (SBEs) incorporated with sodium tetrafluoroborate (NaBF 4 ) are investigated for their suitability in sodium‐ion battery (SIB) technologies. The SBEs were prepared using a solution casting method. The ionic conductivity of the TSP‐NaBF 4 electrolytes was analyzed as a function of salt concentration and temperature via impedance spectroscopy. Results indicated an optimal composition of 70TSP‐30NaBF 4 , achieving a maximum conductivity of 2.68 × 10 − ⁴ S/cm at room temperature (30°C), and exhibiting Arrhenius‐type thermally activated behavior. The ionic transference number (t ion ) was determined using the Wagner polarization method. Linear sweep voltammetry was employed to assess the electrochemical stability window, ensuring compatibility with SIB operation. The optimized electrolyte's practicality was further evaluated through primary SIB discharge studies, demonstrating stable electrochemical performance and reasonable discharge capacity. The study concludes that TSP‐NaBF 4 SBEs offer a promising, eco‐friendly alternative for sustainable energy storage applications.