Anion receptor and heavy metal-free redox mediator decorated separator for lithium-sulfur batteries

The adsorption-catalysis synergy for accelerated conversion of polysulfides is critical toward the electrochemical stability of lithium-sulfur battery (LSB). Herein, a non-metallic polymer network with anion receptor units, trifluoromethanesulfonyl (CF3SO2-) substituted aza-ether, was in-situ integrated on PE separator, working as an efficient host for anchoring lithium thiophosphates (LPS) as redox mediators and polysulfides through Lewis acid-base interaction. The anchored LPS on the modified PE separator displayed a robust chemical adsorption ability towards polysulfides through the formation of S-S bond. Meanwhile, LPS decreased the energy barrier of Li2S nucleation and promoted redox reaction kinetics. The battery with LPS decorated separator revealed a long cycling lifespan with a per cycle decay of 0.056 % after 600 cycles, and a competitive initial capacity of 889.1 mAh/g when the of sulfur cathode increased to 3 mg cm-2. This work developed a new design strategy to promote the utilization of lithium phosphorus sulfide compounds in LSB.