Pencil Drawing Stable Interface for Reversible and Durable Aqueous Zinc‐Ion Batteries

Abstract Zinc‐ion batteries (ZIBs) have been regarded as one of the most promising aqueous energy storage devices due to their low‐cost, high capacity, and intrinsic safety. However, the relatively low Coulombic efficiency caused by the dendrite formation and side reactions greatly hinders the rejuvenation of ZIBs. Here, an utterly simple approach by pencil drawing is employed to improve the poor performance of normal Zn anode and hinders the formation of passivated byproduct as well as serious dendrite growth. Significantly, the functional graphite layer can not only act as ions buffer, but also guide the uniform nucleation of Zn 2+ in graphite voids. With such synergy effect, the graphite‐coated Zn anode (Zn–G) displays low overpotential, high reversibility, and dendrite‐free durability compared with the pristine Zn. Consequently, a low voltage hysteresis of ≈ 28 mV can be achieved and maintained over 200 h. Furthermore, the Zn–G anode is paired with a V 2 O 5 · x H 2 O cathode to construct a rechargeable ZIB. As‐assembled device can output high energy/power density of 324.3 Wh kg −1 /3269.8 W kg −1 (based on the active mass loading in cathode) together with a capacity retention of ≈ 84% over 1500 cycles at a current density of 5 A g −1 .