Synergistic Regulation of Interface Electric Field and Zinc Ion Transport Kinetics via Co‐Doped ZnO Nanocrystals Additive for Highly Reversible Zinc‐Ion Batteries

ABSTRACT Zinc‐ion batteries (ZIBs) are promising for large‐scale energy storage, but their practical applications are still greatly limited by the thermodynamic and kinetic mismatch resulting from uneven interfacial electric fields and sluggish Zn 2+ transport kinetics. Herein, electron‐delocalized Co‐doped ZnO nanocrystals were synthesized as an electrolyte additive to synergistically regulate the local electric field and Zn 2+ transport kinetics of the electrode–electrolyte interface for building efficient ZIBs. Specifically, Co doping induces lattice distortion and facilitates the formation of oxygen vacancies, thereby promoting electron delocalization and redistributing the interface electric field. Meanwhile, combining the electron delocalization strategy with nanocrystals helps to achieve numerous zincophilic sites, thereby accelerating the Zn 2+ transport, resulting in regular and planar Zn deposition. Encouragingly, the Zn//Zn symmetric cell achieves exceptional cycling stability of 2700 h at 10 mA cm −2 and 1 mAh cm −2 with a high cumulative plated capacity of 13 700 mAh cm −2 ; the Zn//Cu asymmetric cell exhibits high reversibility with an average coulombic efficiency of 99.73% for over 3300 h. The strategy of synergistically regulating the interfacial electric field and the Zn 2+ transport kinetics provides a universal route to challenge Zn interface chemistry for advanced ZIBs and could be extended to other aqueous metal‐ion batteries.