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 (similar to 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.