Polybromides Attraction-Repulsion Regulation Promotes High-Performance Zinc-Bromine Static Battery.

Aqueous zinc‑bromine (Zn-Br) static batteries that employ bromine complexing agents offer excellent reversibility and robust cyclability, holding great promise for grid‑scale energy storage. However, the sluggish kinetics of the resulting solid complexes hinder their practical applications. Herein, we develop an attraction-repulsion regulation relying on choline cations (Ch+) and sulfate anions (SO4 2-) to confine the polybromides (Br3 -) and enable fast kinetics. Experiments and theoretical calculations confirm that the strong bonding effect of Ch+ and high negative charge density of SO4 2- prevent the Br3 - from dissolving and shuttling into the electrolyte. Consequently, the Zn-Br static battery with the optimal electrolyte achieves a reversible capacity of 166 mAh g-1 (based on the mass of activated carbon) with an average discharge voltage of 1.73 V at 0.2 A g-1, while maintaining a remarkable rate capability with a high discharge capacity of 99 mAh g-1 at 8 A g-1 and a long lifespan over 15 000 cycles with a capacity retention of 84.9% at 5 A g-1. Moreover, pouch cell under a high areal capacity of 8.3 mAh cm-2 exhibits a discharge capacity of 365 mAh after 100 cycles at 0.05 A g-1. This work establishes a critical pathway toward the subsequent development of Zn-Br static battery.