Porous polymer composite separators with three-dimensional ion-selective nanochannels for high-performance Li–S batteries

Lithium-sulfur (Li–S) batteries have been regarded as one kind of the most attractive candidates for next-generation energy storage devices for their high theoretical energy density and fairly low cost. However, the “shuttle effect” caused by diffusion of soluble polysulfides and uncontrollable growth of lithium dendrite seriously deteriorate the long-term cycle stability and safety of Li–S batteries in practical applications. Herein, a highly porous polyvinyl alcohol (PVA)/sodium carboxylmethyl cellulose (CMC) composite separator with three-dimensional ion-selective nanochannels has been successfully fabricated via a facile non-solvent induced separation method. The abundant negative –COO- groups inside the nanochannels can hinder the undesired polysulfides penetrating through the separator, but allow Li+ transporting rapidly and induce uniform lithium stripping/plating. As a result, the Li–S battery using the porous PVA/CMC composite separator realizes stable cycling with a low decay rate of 0.045% per cycle over 500 cycles at 1 C. This work offers a feasible strategy to design advanced multifunctional Li–S battery separators. [Display omitted] •A highly porous PVA/CMC composite separator with 3D ion-selective nanochannels is facilely fabricated.•The –COO- groups within the porous nanochannels can suppress shuttle effect of polysulfides and growth of lithium dendrite.•The composite separator endows high rate performance and long cycling stability for Li–S batteries.