In this work, electrospun poly(ether sulfone) (PES) nanofibrous membranes coated with hydrophilic polydopamine (PES-PDA) were successfully prepared. As a separator of lithium-ion batteries, the prepared PESPDA nanofibrous membrane shows ultrahigh porosity, due to the extra-large surface area of the nanofibers. Moreover, good thermostability of PES and polydopamine also results in the low shrinkage of the membrane under high temperature. As a result of the large number of amine groups and phenolic hydroxyl groups from the polydopamine, superior electrolyte wettability and high liquid electrolyte uptake capacity of the PES-PDA nanofibrous membrane have also been disclosed through comprehensive study, which would decrease the electrolyte absorption time and improve the performance of the battery. In the cell evaluation, an expected enhancement of cell performance with reduced polarization phenomenon and improved cycling stability is observed after coating with polydopamine, which certifies the validity of the polydopamine coating.