Zn2+ flux regulator to modulate the interface chemistry toward highly reversible Zn anode

Abstract

The persistent challenges of diminished coulombic efficiency (CE) and the formation of Zn dendrites at the Zn anode interface substantially hinder the cycle life of aqueous Zn-ion batteries (AZIBs), thereby impeding their widespread deployment. To address these issues, multifunctional 2-amino-5-guanidino-pentanoic acid (AGPA) additive is introduced into the electrolyte, as a novel Zn2+ flux regulator (ZFR) to improve the reversibility and durability of Zn anodes. The distinctive zincophilicity of amino groups empowers such ZFR with a higher adsorption energy, enabling the construction of a multifunctional molecular adsorption layer on Zn electrode surface. Simultaneously, leveraging the exceptional nucleophilic characteristics of polar carboxyl groups, AGPA molecules tend to form chelating bonds with Zn2+ for manipulating the interface chemistry and solvation chemistry. The functional groups in ZFR work in synergy to attract zinc ions for homogenizing Zn2+ flux and suppress the interfacial side reactions, resulting in uniform dendrite-free Zn deposition. Consequently, the Zn//Zn symmetrical cell achieves an extended cycle life of 5500 h. Moreover, the ZFR enables stable operation of the full batteries with an ultra-long cycling lifespan of 6000 cycles at 5 A/g, showcasing the effectiveness of ZFR in advancing the commercialization of AZIBs.