Unraveling the Carbonyl Charge‐Storage Mechanism in Conjugated Carbonyl‐Based Organic Electrodes for High‐Performance Aqueous Zinc‐Ion Batteries

ABSTRACT Developing carbonyl‐based organic electrodes with multi‐active sites is crucial for advancing aqueous zinc‐ion batteries (AZIBs), but a fundamental understanding of their charge‐storage mechanism remains elusive. Herein, we elucidate this mechanism through the molecular design of a conjugated carbonyl compound ( DHB ) and its oxidized‐derivative ( o‐DHB ). While DHB undergoes a 4‐electron storage process, strategic oxidation expands this to a reversible 6‐electron process in o‐DHB . Remarkably, the resultant Zn||o‐DHB battery delivers an exceptional specific capacity of 323 mAh g − 1 even at a high current density of 5 A g − 1 and retains 71% of its capacity after 3,500 cycles, outperforming most reported organic AZIBs. Combined electrochemical and spectroscopic comparative analyses reveal that the high oxidation potential of terminal ortho‐hydroxyl groups (C─O─H) in DHB inhibits their full utilization. In contrast, o‐DHB enables the reversible reduction of both ortho‐ and para‐C = O groups at relatively low potentials to form C─O─Zn bonds, confirming Zn 2+ migration—not H + insertion—as the dominant charge‐storage mechanism. Theoretical calculations further demonstrate that the oxidation engineering lowers the LUMO energy and narrows the HOMO–LUMO gap of o‐DHB , promoting electron delocalization, enhancing conductivity, and accelerating reaction kinetics. This work provides profound mechanistic insights and establishes a molecular design principle for developing high‐performance organic cathodes for AZIBs.