The Effect of Dimethyl Carbonate Plasticizer on Ionic Conductivity, Ionic Transport and Structure of Carboxylmethyl Cellulose – Ammonium Acetate Solid Biopolymer Electrolytes for Protonic Energy Storage

Solid biopolymer electrolyte (SBEs) systems of carboxylmethyl cellulose doped ammonium acetate (CMC-NH4CH3CO2) and plasticized with dimethyl carbonate (CMC-NH4CH3CO2-DMC) have been successfully prepared by solution casting technique. Both SBE systems were translucent, colorless and flexible with no phase separation. In this research, Fourier Transform Infrared (FTIR) were used to identify the complexation between host polymer, salt and plasticizer. Varian 3100 FT-IR spectrometer Excalibur series analysis reveals the complexation occurred between CMC and NH4CH3CO2 at 1412 cm-1 and 1583 cm-1. No significant complexation is observed with the addition of DMC, hence, DMC has created new pathway and acted as catalyst in the SBEs. The electrical properties of SBEs were investigated using Electrical Impedance Spectroscopy (EIS). The highest conducting CMC-NH4CH3CO2-DMC SBE is (4.27 ± 0.02) x 10-5 S/cm at 10 wt.% DMC. By performing the Transference Number Measurement (TNM), the charge transport in these SBE systems is predominantly ions and the conducting species were identified as cation or protons (H+) which confirmed the FTIR analysis. This work implies that there is a potential application of the present SBE as a new bio-based electrolytes system in the fabrication of electrochemical devices.