Dual Regulation of Zn2+ Desolvation and Deposition via In Situ Grown Crystalline Zn(NCN) on Carbon Nitride for Ultra-Stable Zinc Metal Anodes

Abstract

Aqueous zinc-ion batteries represent a promising candidate for safe and economical energy storage systems. However, their widespread application is hindered by undesirable side reactions and the formation of zinc dendrites at the anode. Graphitic carbon nitride (g-C3N4) has emerged as a promising artificial interphase material due to its layered structure analogous to graphene and its nitrogen-rich composition. Nevertheless, the inherently low crystallinity of conventional g-C3N4 often results in insufficient ionic conductivity and slow Zn2+ kinetics, which restricts its effectiveness in practical interfacial regulation. In this study, a zincophilic Zn(NCN)-CN composite coating is designed to establish a durable and kinetically enhanced Zn/electrolyte interface. The strongly coordinated NCN2–-Zn motifs facilitate the desolvation process of Zn2+ and enhance interfacial ion transfer. Concurrently, numerous zinc-affinitive nitrogen sites ensure a uniform distribution of the interfacial electric field and Zn2+ concentration, thereby suppressing the tip effect and promoting homogeneous zinc deposition without dendrites. Owing to these favorable characteristics, the Zn(NCN)-CN protected anode exhibits remarkable cycling stability in symmetric cells, maintaining operation for more than 5400 h at 0.2 mA cm–2. Furthermore, when assembled with a MnO2-based cathode, the full cell achieves a high discharge capacity of 151.5 mAh g–1 after 2000 cycles at 1.5 A g–1. This study provides an efficient interfacial engineering approach for achieving dendrite-free zinc metal anodes.