Ion conductivity improved polyethylene oxide/lithium perchlorate electrolyte membranes modified by graphene oxide

•Membrane of superior conductivity is achieved at 0.6 wt% of graphene oxide.•Free volume site is crucial in ion transfer of prepared electrolyte membranes.•Network of fast ion pathway develops at ethylene oxide/graphene oxide interface.•d-Spacings of graphene oxide sheets are expanded in membranes prepared.

Polyethylene oxide (PEO)-based solid electrolyte membrane modified via graphene oxide (GO) is prepared. A homogeneous dispersion of GO is achieved in PEO matrix. GO promotes the movement of ethylene oxide (EO) segment at EO/GO interface where the expansion of the free volume void occurs. GO sheets influence the confined helix of EO/lithium-ion (Li+). Composites of GO/Li+/GO, GO/Li+/EO/Li+/GO, and GO/EO/GO are suggested by the X-ray diffraction patterns, structures of which relate to the mechanisms of Li+ dissolving into GO sheets of different concentrations. At 294 K, unexpected 70-fold increase in conductivity of electrolyte membrane is achieved at 0.6 wt% loading of GO. The superior conducting property is attributed to (a) a fine distribution of GO providing interconnected channel at EO/GO interface for fast ion transfer and (b) layered GO-intercalated composites.

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