Biopolymer Electrolytes for Sustainable Energy Storage: Role of Strontium Ion Coordination in Ionic Transport
Nayaka Manjunatha Vilas, T. Sheela, Ismayil, P. C. DhanushABSTRACT
Solid biopolymer electrolytes (SBPEs) containing different concentrations of SrCl 2 ·6H 2 O in methyl cellulose (MC) were prepared by solution casting and characterized using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), dielectric analysis, linear sweep voltammetry (LSV), transference number measurement (TNM), moisture uptake, and mechanical stability tests. XRD and FTIR confirmed enhanced amorphous structure and polymer–salt complexation. The optimized SM20 electrolyte exhibited the highest room‐temperature ionic conductivity of 1.85 × 10 −4 S cm −1 , nearly five orders of magnitude higher than pristine MC (3.34 × 10 −9 S cm −1 ). Improved ion transport was supported by a diffusion coefficient of 7.55 cm 2 s −1 , ionic mobility of 294.05 cm 2 V −1 s −1 , and ionic transference number of 0.76. The electrolyte also showed an electrochemical stability window of 2.90 V and improved thermal stability, with the thermal transition shifting from 165°C to 172°C. Low moisture uptake, good mechanical stability, and an EDLC specific capacitance of 6.9 F g −1 demonstrate its potential for solid‐state energy storage applications.