Ionic Conductivity and Electrochemical Properties of Alginate-NN4NO3-Based Biopolymer Electrolytes for EDLC Application

In this work, alginate doped with various contents of ammonium nitrate (NH4NO3) as a solid biopolymer electrolyte (SBE) was prepared via casting by using distilled water as a solvent. Impedance studies on alginate-NH4NO3 SBE films were conducted via impedance spectroscopy. The lowest bulk resistance (R-b) showed that the maximum ionic conductivity of the sample containing 25 wt.% NH4NO3 at ambient temperature (303 K) was 5.56 x 10(-5) S cm(-1). The temperature dependence of ionic conductivity was evaluated, and results confirmed that electrolytes followed an Arrhenius behavior. The highest conducting sample was fabricated into an electrical double-layer capacitor and characterized in terms of its electrochemical properties through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurement. CV analysis indicated that specific capacitance decreased as the scan rate increased. Conversely, GCD analysis showed that specific capacitance almost remained unchanged for up to 5000 cycles.