A homogeneous plating/stripping mode with fine grains for highly reversible Zn anodes

Abstract

Aqueous zinc metal batteries (AZMBs) have emerged as an attractive energy storage option due to their operational safety, low cost, and environmentally friendly nature. However, the hexagonal close-packed (hcp) Zn anode always exhibits dendritic plating/stripping behavior due to the uncontrollable nucleation and growth of hexagonal platelets, which severely hinders its further development. Herein, we regulate both nucleation and Zn/Zn²⁺ redox kinetics to enable a homogeneous plating/stripping mode with fine grains, significantly improving the stability and reversibility of the Zn anode. Surface overpotential, which directly determines the nucleation behavior, is prominently amplified by the adsorption of added cordycepin (Cor) on the Zn anode surface. Therefore, a promoted nucleation process with the formation of small-sized Zn grains is achieved. The mitigated Zn growth/dissolution rate caused by the strong steric hindrance effect of Cor further ensures the granular morphology after cycling. Owing to this dual regulation strategy, the Zn anode delivers superior cycling stability of the Zn‖Zn symmetric cell over 900 h at 5 mA cm⁻² and an ultra-high cumulative plating capacity of 3 A h cm⁻² at 10 mA cm⁻². The concept also works in Zn‖Cu asymmetric cells and Zn‖NaV₃O₈·1.5H₂O (NVO) full cells, facilitating excellent reversibility and cycling performance. This work presents a new mode for Zn plating/stripping, which will make highly reversible AZMBs achievable.