Enhanced Ion Conductivity in a Poly(ionic liquid)-Grafted Nanoparticle-Based Single-Ion Conductor

Abstract

In contemporary batteries, solid polymer electrolytes are widely prioritized for their easy processability and safety; however, they suffer from limited ionic conductivity. Polymerized ionic liquids (PILs) counter this shortcoming by combining mechanical properties of polyions while allowing the counterions (anions) to maintain their free mobility. Poly(1-vinylimidazolium bistriflimide)-grafted iron oxide (Fe 3 O 4 ) nanoparticles with different chain lengths were synthesized to investigate the effect of grafting the PIL chains on the ionic conductivity. The long-range Coulombic interactions among PIL-grafted chains assist the formation of nanoparticle strings that percolate even at low particle concentrations. Within the percolated network, the connectivity of polycation grafts enabled effective ladder-like ion hopping of TFSI − anions and the cooperative ion motion in nanoparticle networks. The self-assembling nature of nanoparticles, when grafted with polymer electrolyte chains, increased ionic conductivity by promoting the facilitated transport of counterions. Upon incorporating ionic liquid to the PIL-grafted nanoparticles, the presence of ionic clustering was observed to decrease conductivity. Our results demonstrate that the graft chain confinement and particle percolation are essential factors for single-ion conductor design.

Film Thickness Dependence of Surface and Internal Morphology Evolution in Polymer-Grafted Nanocomposites

“…These new observations can lead to improved performance for applications requiring durable barrier coatings . Further, the percolated structures provide a foundation for designing materials with attractive electric and ion conductivity, − crucial for the innovation of electronic and storage technologies as well as batteries.…”