High-Reversibility and Fast-Kinetics Organoselenium-Sulfur Cathodes with Multilectron Bidirectional Redox for Aqueous Zinc-Ion Batteries

Abstract

Abstract Coupled cationic–anionic multivalent redox chemistry enables chalcogen-based cathodes to realize multielectron transfer and high specific capacity in aqueous zinc-ion batteries. However, such redox reactions are inherently dependent on halogen-based electrolytes, which are incompatible with conventional battery systems. Additionally, the synchronous bidirectional valence conversion of chalcogen species suffers from poor reversibility. Targeting this issue, this work constructs a π-conjugated molecular framework where sulfur atoms are covalently embedded between diphenyl diselenide units (DPSeS). The integrated delocalized p‒π conjugation system achieves fully reversible multivalent conversion of Se and S (–2 ↔ +2) in Zn(OTF)2 electrolyte, with the reversible deintercalation/intercalation of OTF– and Zn2+. Compared to pure selenide SeS cathode with the discharge capacity of 159 mAh g–1, this organic selenide compound exhibits higher positive-state utilization and superior electrochemical performance, with an initial discharge specific capacity as high as 848 mAh g–1. This material also delivers outstanding reaction kinetics and cycling stability, which fully demonstrates the remarkable advantages of the organic short-chain Se–S–Se structure in regulating multielectron redox reactions of chalcogen elements. This discovery provides new insights and inspiration for addressing the core bottleneck issues associated with multivalence chalcogenide cathodes in aqueous zinc-ion batteries.