▎ 摘　　要

Graphene, a 2D sp(2)-hybridized carbon sheet is a hot topic in the fields of materials science and chemistry. Here, a symmetrical multilayer architecture of graphene is designed by grafting of sulfonated 4,4- diaminodiphenyl sulfone (SDDS) with the ample sulfonate groups and tunable interlayer spacing to exhibit the Li+ extraction from ionic mixtures with Na+, Mg2+ and Ca2+. Under the application of an electric field, the selective separation of cations can be achieved by controlling the flow channels of negatively charged ions (approximate to 0.48 nm) during the synthesis of rGO-SDDS-rGO membrane. The result shows that the ion selectivity of the rGO-SDDS-rGO membrane is Na+ > Li+ > Ca2+ > Mg2+ and the absolute separation efficiency values of Li+/Mg2+ and Li+/Ca2+ are as high as 85.32 and 80.81%, respectively.