Dual-Site Catalytic Interfaces Synergistically Boost Desolvation and Redox Kinetics in Zinc-Ion Batteries.

Abstract

Aqueous zinc-bromine batteries hold significant promise for large-scale energy storage owing to their intrinsic safety, high operating voltage and low cost. Their deployment, however, is limited by sluggish Zn² ⁺ desolvation at the anode/electrolyte interface and sluggish redox kinetics of bromine species at the cathode. In this work, we developed a dual-site catalytic interface that selectively accelerates interfacial kinetics without altering the bulk electrolyte. On the anode-facing side, the indium acetylacetonate molecules provide soft Lewis acid In³ ⁺ sites that weakly coordinate with water and interact with solvated Zn² ⁺, effectively lowering Zn² ⁺ desolvation energy and enabling uniform, dendrite-free zinc deposition. On the cathode-facing side, the copper acetylacetonate molecules offer redox-active Cu² ⁺/Cu⁺ sites that catalyze the Br⁰/Br^- conversion, accelerating reaction kinetics and improving reversibility. As a result, the desolvation energy barrier decreases by approximately 21% (from 39.69 to 31.25 kJ·mol^-1). The zinc-bromine battery with dual-site interface delivers a high specific capacity exceeding 293.8 mAh·g^-1 at 0.2 A·g^-1, which reaches approximately 87.5% of the theoretical capacity of pure bromine (335.5 mAh·g^-1). Our findings reveal that targeted interfacial catalysis can overcome kinetic bottlenecks in zinc batteries while preserving the intrinsic properties of the electrolyte, offering a general strategy for high-performance energy storage systems.