Focusing on the synergistic interfacial effect: Trace additive achieves long cycling life of Zn anode

Abstract

The electrochemical performance of Zn anodes is significantly compromised by dendritic formation and uncontrolled parasitic reactions during repeated plating/stripping processes. Here, aspartame (APM), a dipeptide analogue, is used as an electrolyte additive to achieve long stable cycling of Zn anodes. This work pioneers the discovery of its dual-functionality in a synchronously engineering H₂O-poor Helmholtz plane (HP) and a self-adaptive organic-inorganic composite solid electrolyte interphase (SEI). Experimental results and theoretical calculations confirm that AMP can regulate the EDL to form H₂O-poor HP through the adsorption of polar groups on the Zn anode surface (adsorption energy, −0.63 eV), and also form an organic-inorganic graded SEI with self-adaptive ability by preferred in situ decomposition (lowest unoccupied molecular orbital (LUMO), −3.001 eV). This synergistic interfacial effect achieves a long cycling life of Zn anode at 1 mA cm⁻² exceeding 5440 h. Additionally, the Zn||Cu asymmetric cell demonstrates an average coulombic efficiency of 99.90 % for 2340 cycles at 5 mA cm⁻² and 1 mAh cm⁻². This work highlights the importance of the construction of H₂O-poor HP and SEI for stabilizing electrode interfaces, providing a universal strategy for metal anode stabilization in aqueous energy storage systems.