Viscosity of Pectin-[BMIM][PF6] electrolytes and the interplay of ion-ion interactions

Polymer embedded ionic liquid type of composite electrolytes are attracting considerable attention for advanced rechargeable batteries, offering enhanced performance, environmental sustainability, and safety. This study employs classical molecular dynamics simulations to investigate a composite electrolyte comprising pectin and 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) IL. We conduct extensive simulations to calculate the viscosity using the Green-Kubo approach and examine the interplay of ion-ion and ion-polymer interactions through radial distribution functions and free energy analyses. Our simulations revealed that the addition of pectin chains leads to a notable increase in viscosity, which scales exponentially with the loading (x) of pectin as η=6.83ex/11 mPa.s. The interplay of competing interactions between the cation–anion and ion-polymer pairs dictates the structural arrangement of ionic species to favor decreasing trends for ion coordination with potential benefits to efficient ionic conductivity within the polymer-IL electrolyte systems. These findings elucidate the multifaceted dynamics of pectin-IL electrolytes, underlining their suitability as advanced battery electrolyte materials.