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 V₂ O₅ //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.

Keywords: Janus separator; Zn metal anodes; in situ grown vertical graphene carpet; vertical graphene.