A permselective protection layer assembled by two-dimensional organic vermiculite produces a highly stable lithium metal anode for lithium-sulfur batteries

Abstract

Designing a protective coating for the lithium metal anode is the crucial yet challenging solution to its practical applications. How to well isolate the reactants in electrolytes but allow fast and uniform ion diffusion is the greatest challenge for various high energy density batteries, e.g., lithium–sulfur batteries. Herein, we propose a permselective protect coating, which has the ability to accelerate the homogeneous fast Li-ion diffusion but block the polysulfide anion penetration, and obtain a dendrite-free and corrosion-resistive lithium metal anode. The above ion-sieving function is realized by a membrane assembled with cetyltrimethylammonium (CTA+)-modified two-dimensional organic vermiculite nanosheets. The enlarged interlayer spacing of the membrane with CTA+ and the negative charges on the vermiculite nanosheets enhance the fast Li-ion transmission across the membrane for uniform Li deposition. At the same time, the non-polar alkyl of CTA+ and the negatively charged surface effectively block the polysulfide adsorption and penetration. Therefore, the side reactions and dendrite growth are effectively suppressed, and with the high sulfur loading (5 mg/cm2) and limited E/S ratio, the assembled lithium–sulfur cell shows good cycling stability at 0.1C, revealing a high capacity retention of 65.9 % over 300 cycles.