Ion Transport Mechanisms in Lamellar Phases of PS-PEO Block Copolymer Electrolytes Doped with LiPF₆ Salts.

We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene-polyethylene oxide (PS-PEO) block copolymer (BCP) electrolytes doped with LiPF6 salts. We compare the results obtained for ion transport in the phase separated BCP melts to those for salt-doped PEO homopolymer melts. The ions were found to exhibit slower dynamics in both the block copolymer and in the PEO phase of the BCP melt compared to those in pure PEO melt. Such results are shown to arise from slower segmental dynamics in the BCP melt and the coordination characteristics of the ions. Further, polymer backbone-ion residence times analyzed as a function of distance from the interface show that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of glassy PS blocks and phase segregation on ion transport properties. Ion transport modes in the BCP melt were also studied and were compared with those in pure PEO melts.