Graphene oxide spontaneous reduction and self-assembly on the zinc metal surface enabling a dendrite-free anode for long-life zinc rechargeable aqueous batteries.

Rechargeable aqueous Zn-based batteries are one of the most promising large-scale energy storage devices, benefiting from their eco-friendliness, low cost, high power/energy densities, and safety advantages without using flammable and poisonous organic liquid electrolytes. However, various challenges, such as infinite volume change and growth of dendrites during the electrostripping/electroplating process, lead to low cycling stability (cell shorting) and hinders the application of Zn-based batteries. Herein, a facile and effective approach to reduce graphene oxide (GO) spontaneously by zinc metal is developed and subsequently, the reduced graphene oxide (rGO) is self-assembled to create a layer-by-layer film on the Zn foil surface. This self-assembled, layered rGO on a Zn surface provides a large electroactive area and a soft substrate for Zn electrodeposition, which significantly mitigates Zn dendritic growth by eliminating its driving force. Compared with bare Zn, this composite anode exhibits much lower overpotential (~20 mV at 1 mA cm−2) and excellent long-life cyclability. A full-device with active carbon demonstrates good rate capacity and superior cycling stability. This well-designed anode also provides a useful solution and the possibility of constructing a dendrite-free advanced zinc anode. This is very important to all the zinc-based batteries for grid-scale storage. Unlabelled Image • A zinc metal anode coated by layered reduced oxide graphene is synthesized. • The approach presented in this work is a spontaneous and self-assembly process. • The reduced oxide graphene coating layer reduces polarization of anodes. • The reduced oxide graphene effectively suppresses the Zn dendrites formation. • This hybrid anode exhibits improved long-term cycling abilityin aqueous battery. [ABSTRACT FROM AUTHOR]