Ag-doped Cu nanoboxes supported by rGO for ultra-stable Zn anodes in aqueous Zn-ion battery

Abstract

Advanced aqueous zinc-ion batteries have been greatly limited application caused by uncontrollable dendrite formation, hydrogen evolution and zinc metal corrosion, which can lead to quick failure of the battery and low Coulombic efficiency. Three-dimensional (3D) porous host strategy is available to limit zinc dendrite growth and electrode interfacial side reactions. Herein, an ingenious local levelling and macro stereo strategy is rationally designed as a Zn plating/stripping scaffold. The flexible 3D carbon cloth as the structural and conductive framework is coated by Ag-Cu-reduced graphene oxide (Ag-Cu-rGO) and Ketjen black. Benefiting from the uniformly dispersed zincophilic Ag on the surface of Cu nanoboxes, the anode suppresses hydrogen evolution side reactions and reduces local current density via more nucleation sites. In addition, rGO homogenizes both the ion flux and electric field at the electrode surface, resulting from high conductivity and large specific surface area of rGO. As a result, the fabricated Zn//Ag-Cu-rGO asymmetric cells exhibit stable voltage profiles for plating and striping 250 cycles, maintain nearly 100% Coulombic efficiency at 2 mA·cm⁻² and 1 mAh·cm⁻² as well as behave an extremely small nucleation overpotential of 34 mV and Ag-Cu-rGO@Zn symmetric cell presents highly uniform electric field with a superior lifespan over 2500 h at 1 mA·cm⁻² and 1 mAh·cm⁻², respectively. Meanwhile, this efficient Ag-Cu-rGO@Zn anode also enables a substantially stable Ag-Cu-rGO@Zn//V₂O₃ full cell over 2000 cycles. The work opens a new avenue of 3D host for durable and dendrite-free flexible aqueous zinc-ion batteries anode.