Successive Redox Mediation Supported by Pnictogen Chalcohalide Enables High‐Performance Zinc–Sulfur Batteries

Sulfur is a promising high‐capacity cathode but suffers from sluggish redox kinetics and severe side reactions in aqueous electrolytes. We introduce pnictogen chalcohalide Bi 12.67 S 18 Br 2 nanorods (abbreviated as Bi‐S‐Br) as a multifunctional cathode material that functions as a sulfur/bismuth reservoir and a catalytic redox mediator (RM). By integrating a trace amount of iodide electrolyte additive, we demonstrate a potential pathway, featuring several redox couples with gradient potentials: I 0 /I − (0.530 V, RM1) > Bi 3+ /Bi 0 (0.308 V, RM2) > S 0 /S 2− (0.144 V vs. standard hydrogen electrode), whose stepwise dual mediation accelerates sulfur redox kinetics. The sulfurphilic Bi‐S‐Br nanorods also strengthen surface Bi–S interfacial interactions, thus localizing active species and suppressing sulfur disproportionation. As a result, Zn||Bi‐S‐Br cells exhibit synergistic discharge plateaus at 0.66 and 0.59 V and deliver a high specific capacity of 792 mAh g Bi‐S‐Br −1 at 0.4 A g −1 , with an energy density of 488.2 Wh kg −1 and a power density of 244.1 W kg −1 , normalized to the Bi‐S‐Br mass. The practical Zn||Bi‐S‐Br pouch cell configuration sustains 250 cycles at 0.8 mA cm −2 with capacity retention of 70.1%. This study elucidated the successive redox mediation strategy for enhanced sulfur redox kinetics, offering a new design principle for high‐performance aqueous energy storage systems.