Directly Grown Vertical Graphene Carpets as Janus Separators toward Stabilized Zn Metal Anodes

Abstract Zinc metal anode has garnered a great deal of scientific and technological interest. Nevertheless, major bottlenecks restricting its large‐scale utilization lie in the poor electrochemical stability and unsatisfactory cycling life. Herein, a Janus separator is developed via directly growing vertical graphene (VG) carpet on one side of commercial glass fiber separator throughout chemical vapor deposition. A simple air plasma treatment further renders the successful incorporation of oxygen and nitrogen heteroatoms on bare graphene. Thus‐derived 3D VG scaffold affording large surface area and porous structure can be viewed as a continuation of planar zinc anode. In turn, the Janus separator harvests homogenous electric field distribution and lowered local current density at the interface of the anode/electrolyte, as well as harnesses favorable zincophilic feature for building‐up uniform Zn ionic flux. Such a separator engineering enables an impressive rate and cycle performance (93% over 5000 cycles at 5 A g −1 ) for Zn‐ion hybrid capacitors and outstanding energy density (182 Wh kg −1 ) for V 2 O 5 //Zn batteries, respectively. This strategy with large scalability and cost‐effectiveness represents a universal route to protect prevailing metal anodes (Zn, Na, K) in rechargeable batteries.