Synthesis, structural properties, thermal behavior, and electrical and electrochemical sensing performance of tamarind seed polysaccharide-lithium nitrate polymer electrolyte

Tamarind seed polysaccharides (TSPs), in conjunction with alkali nitrate, specifically lithium nitrate (LiNO3), were utilized at various concentrations. The aforementioned precursor was dispersed in an aqueous solvent medium using the solution casting route to synthesize thin film polymer electrolytes based on TSP:LiNO3. A comprehensive characterization, incorporating X-ray diffraction (XRD), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), impedance analysis, and linear sweep voltammetry (LSV), was conducted to elucidate key properties, including crystallinity state (crystalline or amorphous), vibrational band shifts, endothermic point characteristics, ionic conductivity, mobility (both cationic and anionic), diffusion coefficients (both cation and anion), transference number, and electrochemical stability. The investigation revealed that the structural properties of the polymer electrolytes are notably influenced by the varying concentrations of LiNO3 in the polymer host. The maximum ionic conductivity was found to be 1.41 × 10⁻³ S cm⁻¹ for the composition of 750 mg TSP:250 mg LiNO3. The electrochemical stability value and transference number of the prepared TSP:LiNO3 are 4 V and 0.68, respectively. Primary lithium-ion cell has been constructed for highest conducting sample which delivered an open circuit voltage of 1.5 V, and also, the discharge profile with 1 MΩ load has been studied.