Ultrathin single-ion sieving membrane with sub-1-nm channels for suppressing Li dendrite growth and polysulfide shuttling

Abstract

Selectively regulating ion migration at the subnanometre scale is a paramount approach to inhibit polysulfide shuttling and suppress Li dendrite growth in lithium–sulfur batteries, but state-of-the-art approaches lack the capacity to selectively separate Li⁺ ions from Li⁺–PS⁻ ion pairs. Herein, inspired by the selectivity of biological ion channels, we constructed a single-ion sieving membrane allowing highly selective migration of Li⁺ ions by synergizing the size effect of sub-1-nm channels of stacked graphene oxide (GO) with the charge effect of negatively charged polydopamine (PDA) molecules located in between. Other than precisely tuning the channel size, PDA is demonstrated to promote the desolvation of Li⁺ ions, enlarge the migration energy barriers between Li⁺ and PS⁻, and therefore improve Li⁺-ion selectivity. Furthermore, the strong covalent bonding between PDA molecules and GO nanosheets fixes channel sizes, ensuring exceptional anti-swelling stability in organic electrolytes. Considering the ultra-thin thickness (60 nm), negligible inactive weight is introduced, outrivaling previous reports. Combining these merits, we achieved dendrite-free Li plating/stripping with ultralong-term reversibility for 4800 h in Li||Li cells and remarkable cyclability for more than 400 cycles with an energy density of 378 W h kg⁻¹ in Li||S pouch cells. Our biomimetic subnanoscale ion-sieving membrane opens an avenue for precise regulation of ion transport in various batteries.