Novel nanofiber-enhanced SPEEK proton-exchange membranes with high conductivity and stability

In this article, a novel proton exchange membrane , shown both high proton conductivity and excellent stability, has been demonstrated, which is simply fabricated by embedding poly(vinylidene fluoride) grafted poly(styrene sulfonic acid) (PSSA-g-PVDF) nanofibers in sulfonated poly (ether ether ketone) (SPEEK) matrix. The novel nanofiber-enhanced membrane (NEM) presents an utlra-high proton conductivity of 720.6 mS/cm, which is 2.4 times higher than the unmodified SPEEK membrane. The long-range continuous proton transport channel built at the interface between the matrix and nanofibers, known as acid-condensed layer, has been directly confirmed by transmission electron microscopy (TEM) measurements for the first time, which illustrates the result. Futhermore, the NEMs are always provided with the excellent dimensional, thermal, and mechanical stability , which benefit from the sturdy three-dimensional network of PSSA-g-PVDF nanofibers. In virtue of the high conductivity and stability, the NEMs have proved to be very promising in fuel cells.