Highly Reversible Zn Electrodeposition Enabled by an Artificial 3D Defect-Rich Conductive Scaffold.

Abstract

Rechargeable Zn metal batteries are attracting intensive attention due to the high capacity and safety of metallic Zn. However, their developments are strongly restricted by the poor reversibility and low areal capacity of anodes, especially at high rates. To achieve homogeneous and rapid Zn deposition is a way to solve these issues intrinsically. Here, we design a three-dimensional (3D) defect-rich conductive scaffold as an ideal substrate for Zn electrodeposition, which is built up of vertically aligned porous vanadium trioxide nanosheet skeleton supporting defective networks to provide fast electron- and ion-transfer paths. The abundant defects act as the energetically favorable nucleation sites inducing the in situ uniform growth of hierarchical Zn nanosheets on the substrate. The as-electrodeposited 3D Zn anodes achieve exceptionally reversible Zn plating/stripping over 5000 h at both moderate and high current densities (6 and 20 mA cm-2). The 100 A h cm-2 cumulative capacities at 80% depth of discharge are impressive and magnitude of orders greater than the reported Zn anodes so far. The unique 3D defective structure can be well maintained in thousands of cycles, which ensures a remarkably high Coulombic efficiency of 99.99956%. A full cell assembled with the ZnHCF cathode demonstrates a high-capacity retention of 91.2% at 2 A g-1 after 20,000 cycles, over 10 times that of a Zn plate anode. This work provides an eligible anode for advanced rechargeable Zn metal batteries.