▎ 摘　　要

In this present work, a proton-conducting solid biopolymer electrolyte membrane that consists of sodium alginate (SA) incorporated with ammonium formate (NH4HCO2) has been prepared by solution casting technique. Using the highest proton-conducting membrane, electrochemical devices like battery and fuel cell have been constructed. Graphene quantum dot has been used as an additive to highest conducting polymer electrolyte (30 M.wt%SA:70 M.wt%NH4HCO2). The prepared membranes (SA:NH4HCO2) were subjected to various characterization techniques such as XRD, FTIR, DSC, Ac impedance technique, and LSV. On increasing salt concentration, XRD analysis shows that amorphous nature increases. Highest amorphous nature has been found for 30 M.wt%SA:70 M.wt%NH4HCO2. The complex formation between SA and NH4HCO2 has been confirmed by FTIR measurements. The glass transition temperature, T-g, has been measured using DSC (differential scanning calorimetry). 30 M.wt%SA:70 M.wt%NH 4 HCO2 membrane shows a highest ionic conductivity value of 2.77 x 10(-3) S cm(-1). The addition of 1.25 ml GQD into the 30 M.wt%SA:70 M.wt%NH4HCO2 biopolymer electrolyte membrane has improved the value of ionic conductivity to 2.01 x 10(-2) S cm(-1). Transference number analysis reveals that the conductivity is mainly due to the ions in the polymer electrolyte (Wagner's polarization method). LSV technique is used to measure the electrochemical stability of the biopolymer electrolyte membrane which resulted with 1.90 V (without GQD) and 2.08 V (with GQD). Battery constructed with highest ionic conducting membrane shows an open circuit voltage of 1.77 V (without GQD) and 1.79 V (with GQD). A fuel cell has been constructed using highest conducting biopolymer electrolyte membrane and the open circuit voltages of 707 mV (without GQD) and 778 mV (with GQD) have been measured.