Utilizing sodium salt complexed with biopolymer as ionic-conducting electrolyte membrane: a study of morphology, structure and ionic conductivity

In this work, we constructed solid-state membranes by dissolving a combination of starch and sodium hydrogen sulfate in distilled water and glycerin, making use of the established solution casting technique. As the concentration of SHS increased, the membranes became increasingly opaque and displayed notable morphological changes. The surface texture became rough, lumpy and uneven, featuring prominent folds and wrinkles. Structurally, these membranes were predominantly amorphous, with a coarse, flat surface. The membrane having 15 wt.% salt showed the highest ionic conductivity, measured at 3.17 × 10⁻⁵ S cm⁻¹. We propose that these solid biopolymer electrolytes have promising potential as dual-function membranes, serving as both separators and electrolytes in the design of solid-state batteries.