A cost-effective pyrrole additive for realizing highly stable Zn anode

Abstract

In recent years, researchers have increasingly focused on aqueous rechargeable Zn-ion batteries (AZIBs) as a cost-effective and safe alternative to lithium-ion batteries for energy storage. Nevertheless, the limited reversibility of the Zn anode and the low coulombic efficiency of the electroplating process limit the application of AZIBs. In this work, pyrrole is employed as a cost-effective electrolyte additive for stabilizing the Zn anode for the first time. By altering the coordination environment of Zn (H₂O)₆²⁺, chemical and hydrogen evolution corrosion was reduced, and a molecular interface layer was in-situ constructed on the surface of the metal Zn anode, thus effectively inhibiting the corrosion of Zn anode and the growth of dendrites. In addition, the molecular interface layer based on pyrrole can effectively regulate the uniform deposition of Zn ions and limit the 2D diffusion of Zn ions. Therefore, the electrochemical performance of the metal Zn anode is greatly improved in the pyrrole-based electrolyte. At the current density of 1 mA·cm⁻², the stable cycle can exceed 1200 h, and the average Coulomb efficiency is as high as 99%. Moreover, the full battery can have more than 400 stable cycles with a reversible capacity 247.9 mAh·g⁻¹ at a current density 0.5 A·g⁻¹ when assembled with V₂O₅ cathodes. This work provides a simple and feasible strategy for realizing the high performance of aqueous Zn-ion batteries.

Graphical Abstract