Nanoscale Confinement Effects on Ionic Conductivity of Solid Polymer Electrolytes: The Interplay between Diffusion and Dissociation

作者：Chen, Xiupeng; Kong, Xian^*

来源：Nano Letters, 2023, 23(11): 5194-5200.

DOI：10.1021/acs.nanolett.3c01171

• solid polymer electrolytes
• nanoconfinement
• ionic conductivity
• ion correlation
• moleculardynamics simulation

Solidpolymer electrolytes (SPEs) are attractive for next-generationlithium metal batteries but still suffer from low ionic conductivity.Nanostructured materials offer design concepts for SPEs with betterperformance. Using molecular dynamics simulation, we examine SPEsunder nanoscale confinement, which has been demonstrated to acceleratethe transport of neutral molecules such as water. Our results showthat while ion diffusion indeed accelerates by more than 2 ordersof magnitude as the channel diameter decreases from 15 to 2 nm, theionic conductivity does not increase significantly in parallel. Instead,the ionic conductivity shows a nonmonotonic variation, with an optimalvalue above, but on the same order as, its bulk counterparts. Thistrend is due to enhanced ion association with decreasing channel size,which reduces the number of effective charge carriers. This effectcompetes with accelerated ion diffusion, leading to the nonmonotonicityin ion conductivity.