An experimental and theoretical correlation to account for the effect of graphene quantum dots on the ionic conductivity of poly(ethylene oxide) polymer electrolytes

Improving ionic conductivity for poly(ethylene oxide) (PEO) electrolyte has been intensely investigated, while PEO is considered as an appealing solid electrolyte for all-solid-state batteries. Fillers are one of the most successful strategies for ionic conductivity enhancement of polymer electrolyte. It could not only hinder PEO crystallinity, but also provide the favorable conduction pathways for ionic transport between the filler surface groups and the ionic species, thus successfully increasing the ionic conductivity. However, fillers as nanoscale or microscale materials tend to aggregate in PEO polymer electrolyte, preventing ionic conductivity enhancement. Herein, the graphene quantum dots have been used as fillers to improve the ionic conductivity of PEO solid electrolyte. Given the well-dispersed graphene quantum dots, a uniform PEO polymer electrolyte with an improved ionic conductivity up to 1.6 x 10(-5) S/cm can be obtained. Moreover, the influence mechanism of graphene quantum dots on PEO ionic conductivity has been investigated with molecular dynamics simulations. It could provide an atomic-scale insight to the structure-dynamics properties, which contributes to the polymer solid electrolyte improvement and application.