Quantifying Asymmetric Zinc Deposition: A Guide Factor for Designing Durable Zinc Anodes

Abstract

Zinc metal is recognized as the most promising anode for aqueous energy storage but suffers from severe dendrite growth and poor reversibility. However, the coulombic efficiency lacks specificity for zinc dendrite growth, particularly in Zn||Zn symmetric cells. Herein, a novel indicator (f<inf>D</inf>) based on the characteristic crystallization peaks is proposed to evaluate the growth and distribution of zinc dendrites. As a proof of concept, triethylenetetramine (TETA) is adopted as an electrolyte additive to manipulate the zinc flux for uniform deposition, with a corroborating low f<inf>D</inf> value. A highly durable zinc symmetric cell is achieved, lasting over 2500 h at 10 mA cm⁻² and 400 h at a large discharge of depth (10 mA cm⁻², 10 mAh cm⁻²). Supported by the low f<inf>D</inf> value, the Zn||TETA-ZnSO<inf>4</inf>||MnO<inf>2</inf> batteries overcome the sudden short circuit and fast capacity fading. The study provides a feasible method to evaluate zinc dendrites and sheds light on the design of highly reversible zinc anodes.