Enhancing ionic conductivity in biodegradable cellulose acetate polymer electrolytes through formamide-induced...

Developing Solid Polymer Electrolytes (SPEs) is crucial in recent days due to their potential applications in addressing global challenges in sustainable energy systems and providing cost-effective solutions for various industrial applications. Therefore, in this work, a biodegradable, environmentally friendly non-toxic cellulose acetate (CA) based SPE has been developed for proton battery applications by considering CA as a host polymer, NH₄Br as a proton conducting salt and formamide as a plasticizer through a cost effective and facile solution casting method. Formamide, as a plasticizer, promotes effective dissociation of NH₄Br and improves polymer chain flexibility, as evidenced by impedance and SEM analyses. The effect of varying formamide concentrations on the structural and ionic conductivity of the CA matrix was presented in the present report. The highest ionic conductivity of about 1.62 × 10^-3 S/cm was achieved for the SPE containing 1 g of CA, 0.15 g of NH₄Br and 0.8 g of formamide. X-ray diffraction analysis revealed that this concentration led to a higher degree of amorphousness in the polymer matrix, which is crucial for facilitating ionic transport. The findings suggest that the strategic use of formamide as a novel plasticizer significantly improves the conductivity while establishing the CA-NH₄Br-formamide system as a promising free-standing SPE for next-generation proton-conducting energy devices.