Enhanced Ion Conductivity of Poly(ionic Liquid)-Grafted Nanoparticle-based Hybrid Electrolytes

Poly(ionic liquid) (PIL)-grafted nanoparticles are designed with chains that interact with surrounding free ionic liquid medium, and the arrangement of these particles can help to enhance ion conductivity. Specifically, poly(1-vinylimidazolium bistriflimide)-grafted iron oxide nanoparticles with different chain lengths were synthesized to understand the role of grafting the PIL chains on ionic conductivity. The long-range Coulombic interactions between PIL-grafted chains induce the formation of percolated strings at low particle concentrations in ionic liquid/cosolvent mixtures. The high conductivity of this new hybrid system is attributed to the confined polycationic grafts and cooperative ion motion between the grafted particle networks. The measured property is explained by the ladder mechanism of ion hopping in polyelectrolytes. This study shows the importance of chain confinement and particle percolation for the single-ion conductor design.