Carboxymethyl Cellulose–Ammonium Formate Biopolymer Electrolyte: Ionic Conductivity and Electrical Properties

Abstract

Safety concerns about conventional batteries such as prone to leakage, fire and expensive core materials can be overcome by using a solid biopolymer electrolyte (SBE) in the battery system. This work aims to improve the ionic conductivity of the biopolymer electrolyte based on carboxymethyl cellulose (CMC) by doping with varied ammonium formate (AFT) composition (5 – 50 wt.%). The biopolymer electrolyte was tested for its electrical properties, using electrical impedance spectroscopy (EIS) to determine the optimum salt concentration with the highest ionic conductivity. The sample which has the highest ionic conductivity is the sample added with 50 wt.% of ammonium formate which obtained at ~1.47 × 10^-4 S/cm. Surprisingly, this SBE system shows percolation conductivity behaviour. Within 303K– 373K temperature range, the SBE follow Arrhenius behaviour. The charge carrier’s transport properties improved with AFT composition where the dielectric value and relaxation peak position increases with AFT. The maximum ionic conductivity achieved, and the temperature stability shows a promising prospect of current work for energy storage application, albeit further improvement is still needed.