Nanoparticle-based electrolytes, in which nanoparticles are embedded in ion-conducting solid polymers or liquids, have emerged as a promising platform for achieving high lithium transference numbers. In lithium-salt doped polymer electrolytes, the addition of nanoparticles has been reported to increase t Li + . Single-ion conduction (t Li + ≈ 1) was recently observed for nanoparticle-based lithium salts in polymeric matrices and oligomeric solvents. In the latter systems, anion immobilization was achieved by grafting the anionic species onto the surface of nanoparticles. For instance, in the experimental system reported by Schaefer et al., silica nanoparticles were cofunctionalized with polyethylene glycol ligands and tethered anionic species coupled to Li + ions. When dispersed in a conducting fluid such as tetraglyme, a maximum ionic conductivity of ∼ 10 -4 S/cm was observed at an optimal nanoparticle loading. Interestingly, an order of magnitude increase in conductivity was realized by modifying the tethered anion from -SO - 3 to -SO 3 BF - 3 .