High-reversibility Sulfur Anode for Advanced Aqueous Battery.

Despite being extensively explored as cathodes in batteries, sulfur (S) can function as a low-potential anode by changing charge carriers in electrolytes. Here, we report a highly reversible S anode that fully converts from S 8 0 to S 2- in static aqueous S-I 2 batteries by using Na + as the charge carrier. This S anode exhibits a low potential of -0.5 V (versus standard hydrogen electrode) and a near-to-theoretical capacity of 1404 mA h g -1 . Importantly, it shows significant advantages over the widely-used Zn anode in aqueous media by obviating dendrite formation and H 2 evolution. To suppress "shuttle effects" faced by both S and I 2 electrodes, a scalable sulfonated polysulfone (SPSF) membrane is proposed, which is superior to commercial Nafion in cost (US$1.82 m -2  versus $3500 m -2 ) and environmental benignity. Because of its ultra-high selectivity in blocking poly-sulfides/iodides, the battery with SPSF displays excellent cycling stability. Even under 100% depth of discharge (DoD), the battery demonstrates high capacity retention of 87.6% over 500 cycles, outperforming Zn-I 2 batteries with 3.1% capacity under the same conditions. These findings broaden anode options beyond metals for high-energy, low-cost, and fast-chargeable batteries. This article is protected by copyright. All rights reserved.