Self-assembled zinc polyethylenimine shield for long-lasting zinc anodes

Abstract

The zinc (Zn) anode of aqueous zinc-ion batteries (AZIBs) faces significant challenges, including dendritic growth, hydrogen evolution reactions, and corrosion, which impede their commercial application. Here, we present a strategy for creating an artificial surface coating layer, Zn-polyethylenimine (Zn-PEI) coordination polymer, formed on the Zn anode surface. The robust Zn-PEI protective layer, rich in amine groups, accelerates ion transport and provides a uniform electric field, thereby suppressing dendrite formation. Additionally, this layer prevents direct contact between the Zn surface and the electrolyte, reducing other side reactions such as hydrogen evolution, surface corrosion, and passivation. The charged amine groups in PEI preferentially expose the Zn (101) crystal plane, which has weak thermodynamic stability, to achieve ordered and densely packed Zn (101) deposition. Consequently, Zn-PEI@Zn//Zn-PEI@Zn symmetric cells exhibit a remarkable cycling life of over 2000 h under the conditions of 1 mA cm⁻² and 1 mAh cm⁻², and Zn-PEI@Zn//Cu asymmetric cells maintain an average coulombic efficiency of 99.7 % after 1000 stable cycles. This strategy effectively addresses the inherent issues of dendrite growth and hydrogen evolution in Zn anodes, laying a solid foundation for the development of high-performance AZIBs.