Electrical and transport properties of NH4Br-doped cornstarch-based solid biopolymer electrolyte

In this work, cornstarch-based electrolytes are doped with ammonium bromide (NH4Br) and plasticized with glycerol. Starch-NH4Br complexation is evidenced from the Fourier transform infrared (FTIR) spectroscopy results. A room temperature conductivity of (5.57±1.88)×10 S cm obtained by 70wt% starch–30 wt% NH4Br electrolyte is enhanced to (1.80±0.26)×10 S cm with the addition of 30 wt% glycerol. All electrolytes exhibit Arrhenius behavior. The conduction mechanism of 70 wt% starch–30 wt% NH4Br electrolyte and 49 wt% starch–21 wt% NH4Br–30 wt% glycerol electrolyte follows overlapping large polaron tunneling (OLPT) and correlated barrier hopping (CBH)models, respectively. The transference number of ion (tion) and proton (tp) is found to be 0.98 and 0.35, respectively, for 49 wt% starch– 21 wt% NH4Br–30 wt% glycerol electrolyte. The decomposition voltage of 49 wt% starch–21 wt% NH4Br–30 wt% glycerol electrolyte is 1.66 V.