Molecular simulations of ssDNA/ssRNA in [BMIM][PF6] ionic liquid: a novel biopolymer electrolyte for rechargeable battery applications

Abstract

Single-stranded DNA (ssDNA) in ionic liquids (ILs) represents an unexplored class of polymer electrolytes with significant potential for rechargeable battery applications. This study investigates ssDNA + [BMIM][PF₆] systems using all-atom molecular dynamics simulations with OL15/OL3 force fields for DNA/RNA and an optimized OPLS-AA force field for [BMIM][PF₆]. Density profile analysis reveals that ssDNA + IL systems maintain an isotropic distribution of ions. Radial distribution functions and ion association probabilities indicate that the addition of ssDNA preserves the liquid structure of neatIL. Further, the negatively charged phosphate groups in the polymer backbone form a contracted solvation shell with the cations, which leads to smaller cation–anion clusters. A comprehensive analysis of ion diffusion, conductivity, ion-pair relaxation, and viscosity shows that while ssDNA–IL electrolytes exhibit an ionic conductivity 20–30 times lower than neat IL, their mechanical stability improves by a factor of 200–300. These findings establish ssDNA + IL systems as mechanically robust, biodegradable, and high-performing candidates for next-generation battery technologies.