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. CF3 SO3 - anions in the IL operating as Zn2+ -transfer channels is reported. Moreover, the PEDOT:PSS network retains the IL, which renders Zn2+ -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, S6 2- is dominantly reduced by Zn to S2- (S6 → S2- ). During the charging phase, these short chains are oxidized to form long-chain Znx Liy S3-6 . 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.
Keywords: aqueous batteries; ionic liquid films; sulfur cathodes; zinc ion batteries; zinc/sulfur batteries.
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