Thiosulfate-Mediated Polysulfide Redox for Energetic Aqueous Battery

Abstract

Sulfur-based aqueous batteries (SABs) are regarded as promising candidates for safe, low-cost, and high-energy storage. However, the sluggish redox kinetics of polysulfides pose a significant challenge to the practical performance of SABs. Herein, we report a unique redox regulation strategy that leverages thiosulfate-mediated ligand-chain interaction to accelerate the polysulfide redox process (S⁰/S²⁻). The S₂O₃²⁻ species in the electrolyte can induce the rapid reduction of polysulfide through a spontaneous chemical reaction with sulfur species, while facilitating the reversible oxidation of short-chain sulfides. Moreover, the thiosulfate redox pair (S₂O₃²⁻/S₄O₆²⁻) within the K₂S₂O₃ electrolyte contributes additional capacity at higher potential (E⁰ >0 V vs SHE). Consequently, the elaborate SAB delivers an unprecedented K⁺ storage capacity of 2470 mAh g_s⁻¹, coupled with a long cycling life exceeding 1000 cycles. Remarkably, thiosulfate-mediated SAB achieves an energy density of 616 Wh kg_S+Zn⁻¹, surpassing both organic K–S batteries and conventional aqueous battery systems. This work elucidates the mechanism underlying the thiosulfate-mediated polysulfide redox process, thereby opening a pathway for the development of high-energy aqueous batteries.