A Coordination Supramolecular Network Janus Separator Boost Sulfur Redox Dynamics in Lithium-Sulfur Batteries.

Abstract

Lithium-sulfur (Li-S) batteries are limited in practical application due to the dissolution and shuttle effect of lithium polysulfides (LiPSs) intermediates. Herein, a multifunctional Janus separator is designed that integrates the zirconium-based coordination supramolecular network (Zr-CSN) with the polypropylene (PP) membrane to fabricate Zr-CSN@PP. The Zr-CSN@PP constructs a barrier on the side of the sulfur cathode to block the passage of polysulfides, and the nanoporous structure of Zr-CSN transfers lithium ions quickly. The active zirconium sites and abundant oxygen-containing groups of Zr-CSN adsorb and catalyze the polysulfides effectively, which has been proved by experiments and theoretical calculations. Zr-CSN@PP promotes the migration of Li⁺ (the lithium-ion transference number is 0.63) and improves the kinetics of sulfur evolution reactions, enhancing the electrochemical performance of Li-S batteries. The Li-S battery with Zr-CSN@PP separator has a capacity of 650.63 mAh g^-1 after 280 cycles at 0.5 C (average decay of 0.2% per cycle), and a capacity of 422.48 mAh g^-1 after 400 cycles at 2 C. This concept of porous coordination supramolecular networks Janus separator provides a broad prospect for advanced Li-S batteries.