Na-ion conducting biopolymer electrolyte based on tamarind seed polysaccharide incorporated with sodium perchlorate for primary sodium-ion batteries

Bio-based solid polymer electrolytes are synthesized and characterized for the application of sodium-ion conducting batteries. Biopolymer tamarind seed polysaccharide (TSP) has been chosen as the host polymer and ionic dopant of sodium perchlorate (NaClO 4 ) in various compositions (0.5 g to 0.9 g) added to the host polymer as a source of charge carriers. Simple solution casting technique is utilized for the synthesis of solid biopolymer electrolyte membranes. X-ray diffraction analysis has been used to analyze the nature (crystalline/amorphous) of prepared biopolymer membranes. The complex formation between the host biopolymer and sodium perchlorate has been examined with the help of FTIR spectroscopy analysis. Glass transition temperatures (T g ) of the membranes are observed using differential scanning calorimetry (DSC). Ionic conductivities of the membranes are determined from the Ac impedance technique. Among the prepared biopolymer electrolytes, 1 g TSP with 0.8 g of NaClO 4 exhibits the optimum ionic conductivity of 1.70 × 10 −3 S cm −1 . Electrochemical stability window for the optimum conducting biopolymer electrolyte is found to be 3.24 V by linear sweep voltammetry (LSV). The open-circuit cell potential of 3.15 V is observed by fabricating primary sodium battery using the highest conducting biopolymer electrolyte (1 g TSP: 0.8 g NaClO 4 ).