Enhanced Proton Conduction in Bio‐Based Alginate–PVA Polymer Electrolytes via Ethylene Carbonate Plasticization

The development of bio‐derived polymer electrolytes with enhanced ionic conduction is crucial for sustainable energy technologies. This study examines the influence of ethylene carbonate (EC) as a plasticizer on proton transport within alginate–polyvinyl alcohol (PVA) polymer blends doped with ammonium iodide (NH 4 I). Electrolyte films were fabricated via solution casting, and the impact of EC composition on structural, thermal, and ionic properties was systematically evaluated. FTIR analysis confirmed that EC promotes H + dissociation by interacting with the OH and COO − groups of the polymer matrix. Thermogravimetric and differential scanning calorimetry analyses revealed improved thermal properties and reduced glass transition temperature with increasing EC. Electrochemical impedance spectroscopy showed a maximum ionic conductivity of 2.42 × 10 −4 S/cm at 4 wt% EC, consistent with Arrhenius‐type thermally activated behavior. The proton transference number ( t H + = 0.57) indicated dominant cationic conduction. These findings demonstrate the potential of EC‐plasticized bio‐based polymer blends as efficient proton‐conducting electrolytes for next‐generation electrochemical applications.