Sulfur electrode tolerance and polysulfide conversion promoted by the supramolecular binder with rare-earth catalysis in lithium-sulfur batteries

Abstract

The binder that maintains electrode integrity and provides electron/ion transport channels is insufficient for high-performance lithium-sulfur (Li-S) batteries. Multifunctional and environmentally friendly binders with minimal lithium polysulfides (LiPSs) escape and accelerated LiPSs conversion kinetics are critical for sustainable Li-S batteries. Herein, we proposed a new versatile supramolecular polymer binder synthesized by hydrogen bonding crosslinking between hydrolysable polymer matrix and yttrium-pyridine complex in aqueous solutions, denoted as GB-Y. This unique environmental-friendly binder based on supramolecular chemistry could (1) maintain the integrity of sulfur cathode through the mechanical toughness contributed by synergistic effect of hydrogen bonds and robust chemical bonds, (2) anchor LiPSs by lithiophilic effects, and (3) accelerate LiPSs conversion by electrocatalysis of rare-earth catalysis sites (Y3+) as Lewis acids. With above benefits of GB-Y binder, the Li-S batteries with GB-Y binder deliver a high discharge capacity of 1201.5 mAh g−1 and an excellent cyclability over 800 cycles. This binder exhibits a commercial potential in view of capacity release under high-sulfur loading of 6.56 mg cm−2 with lean electrolyte (electrolyte/sulfur (E/S) ratio of 10 μl mg−1). This study provides a concept of binders with three efficacies, i.e. adhesion, adsorption, and catalysis, and offers an innovative and environmentally friendly strategy for the construction of advanced binder with supramolecular chemistry manner to promote the practical application of Li-S batteries.