Advanced Aqueous Zinc‐Ion Battery Cathode With an Ultra‐Flat Discharge Plateau Enabled via Synergistic Crystallization and Host‐Guest Recognition

ABSTRACT Aqueous zinc‐ion batteries (AZIBs) based on quinone cathode have emerged as promising candidates for energy storage systems due to their high theoretical capacity and redox potential. However, achieving an ultra‐flat long discharge plateau remains a critical challenge, largely limited by dynamic changes in quinone molecular packing states and electronic conduction‐ionic migration of quinone. Herein, an 18‐crown‐6 (18C6) template was employed to effectively promote the recrystallization of anthraquinone (RAQ) for the cathode via a simple structure‐directed co‐crystallization method. The template‐assisted RAQ (T‐RAQ) cathode achieves an ultra‐flat, long discharge plateau (voltage fluctuation <1 mV over 90% of the process) and a high specific capacity of 280 mAh g ⁻¹ at 0.08 A g ⁻¹ , with its plateau accounting for 92% of the total discharge capacity. Systematic experimental and theoretical analyses confirm that the introduction of 18C6 effectively improves the recrystallization quality of AQ, thereby enhancing ion transport, electronic conduction, and the exposure of carbonyl active sites, and consequently boosting the electrochemical kinetics and reversibility of the battery. This work provides a novel design strategy for high‐performance AZIBs through the manipulation of crystallization and host‐guest recognition, informing a clear path toward their practical application.