Oxygen‐Rich Carbon Quantum Dots Enable Multiscale Synergistic Regulation for Ultralong‐Life Aqueous Zinc‐Ion Batteries

ABSTRACT The practical application of aqueous zinc‐ion batteries (AZIBs) is now threatened by irreversible parasitic processes at the Zn anode. Here we report a molecular‐scale interfacial engineering strategy using oxygen‐rich carbon quantum dots (o‐CQDs, 38.83 wt% oxygen) that spontaneously self‐assemble into a 2D ion‐transport network in ZnSO 4 electrolyte. This architecture enables multiscale synergistic regulation. First, o‐CQDs induce reconstitution of the primary solvation sheath into a stable [Zn(H 2 O) 4 (o‐CQDs)] 2+ complex, reducing the desolvation barrier from 23.6 to 17.8 kJ mol −1 . Furthermore, the continuous 2D network elevates the Zn 2+ transference number from 0.51 to 0.85 and ionic conductivity enhanced from 40 to 93 mS cm −1 . At the electrode interface, a protective electric double layer promotes preferential Zn(002) deposition while effectively excluding reactive water species. Thus, the Zn//Zn symmetric cells achieve a long cycling life (>10 000 h) and high average Coulombic efficiency (99.6%). Full cells employing the commercial activated carbon as cathode retain >96.1% capacity after 100 000 cycles. More importantly, it can work in a wide temperature range from −10°C to 60°C, with obvious self‐healing capability. This work establishes a synergistic regulation method by using a functional carbonic additive to optimize interfacial engineering to achieve durable zinc‐based energy storage devices.