Initiating a Reversible Aqueous Zn/Sulfur Battery through a “Liquid Film”
Yuwei Zhao, Donghong Wang, Xinliang Li, Qi Yang, Ying Guo, Funian Mo, Qing Li, Chengxin Peng, Hongfei Li, Chunyi Zhi
Abstract
Abstract Sulfur cathodes have been under intensive study in various systems, such as Li/S, Na/S, Mg/S, and Al/S batteries. However, to date, Zn/S chemistry has never been reported. The first reliable aqueous Zn/polysulfide system activated by a “liquid film” comprising 4‐(3‐butyl‐1‐imidazolio)‐1‐butanesulfoni ionic liquid (IL) encapsulated within PEDOT:PSS. CF 3 SO 3 − anions in the IL operating as Zn 2+ ‐transfer channels is reported. Moreover, the PEDOT:PSS network retains the IL, which renders Zn 2+ ‐transfer channels and a polysulfide cathode with enhanced structural stability. The Zn/polysulfide system delivers extraordinary capacity of 1148 mAh g −1 and overwhelming energy density of 724.7 Wh kg −1 cathode at 0.3 Ag −1 . During the discharging phase, S 6 2− is dominantly reduced by Zn to S 2− (S 6 → S 2− ). During the charging phase, these short chains are oxidized to form long‐chain Zn x Li y S 3‐6 . A further optimized high‐concentrated salt electrolyte is used to improve the reversibility of the battery, demonstrating an extended lifetime over 1600 cycles at 1 Ag −1 with a capacity retention of 204 mAh g −1 . This facile approach and the superior performance of the developed aqueous Zn/S chemistry provide a new platform for sulfur‐based battery and potentially solve the problems of other metal/sulfur batteries.