Rechargeable Iron-Sulfur Battery without Polysulfide Shuttling

Sulfur represents one of the most promising cathode materials for next-generation batteries; however, the widely observed polysulfide dissolution/shuttling phenomenon in metal-sulfur redox chemistries has severely restricted their applications. Here it is demonstrated that when pairing the sulfur electrode with the iron metal anode, the inherent insolubility of iron sulfides renders the shuttling-free nature of the Fe-S electrochemical reactions. Consequently, the sulfur electrode exhibits promising performance for Fe2+ storage, where a high capacity of approximate to 1050 mAh g(-1), low polarization of approximate to 0.16 V as well as stable cycling of 150 cycles are realized. The Fe-S redox mechanism is further revealed as an intriguing stepwise conversion of S-8 <-> FeS2 <-> Fe3S4 <-> FeS, where a low volume expansion of approximate to 32.6% and all-solid-state phase transitions facilitate the reaction reversibility. This study suggests an alternative direction to exploit sulfur electrodes in rechargeable transition metal-sulfur batteries.