The Effect of NH4Br Composition on Electrical Behaviour of 2-Hydroxyethyl Cellulose Solid Biopolymer Electrolytes

Abstract

In this study, solid biopolymer electrolytes (SBEs) were developed as an alternative to liquid electrolytes for battery applications. 2-hydroxyethyl cellulose (2HEC) served as the polymer host in the preparation of SBE films, incorporating varying amounts of ammonium bromide (NH₄Br). The films were then analysed using electrical impedance spectroscopy (EIS) to investigate its electrical properties. The system containing 20 wt.% of NH₄Br achieved the highest conductivity at 3.9510^-5 Scm^-1 at ambient temperature of 303 K. The 2HEC-NH₄Br SBE film system was subjected to temperature variations between 303 K – 373 K in increments of 10 °C, revealing an increase in conductivity with rising temperature. This observation suggests that the SBE system adheres to the Arrhenius law, enabling the determination of the activation energy (E_a) through temperature dependence plotting. The E_a for the most conductive system reflects the lowest energy, indicating minimal energy required for the excitation process within the polymer chain. This E_a value offers a deeper insight into the transport parameters, including the number of mobile ions, ions mobility and diffusion coefficient, as determined through the Rice and Roth method.