Stable dendrite-free Zn anode with Janus MXene-Ag interfacial bifunctional protective layer for aqueous zinc-ion batteries

Abstract

The problem of disordered dendrite growth and uncontrollable interfacial side reactions on Zn metal anodes remains a serious challenge for the practical application of aqueous zinc-ion batteries. Herein, we construct a Janus bifunctionally structured MXene-Ag interfacial protective layer on the Zn anode through a simple displacement reaction and electrostatic self-assembly method. The MXene-Ag@Zn anode with hierarchical distribution has superhydrophilicity, abundant zincophilic nucleation sites, and uniform electric field distribution, achieving highly reversible cycle stability in electrochemical tests. The hydrophilic MXene layer accelerates the desolvation of hydrated zinc ions and also prevents direct contact between the electrolyte and the zinc anode, effectively inhibiting interfacial side reactions. On the other hand, zincophilic Ag nanoparticles act as nucleation sites, lowering the energy barrier for nucleation and directing the deposition of zinc ions. Benefiting from the synergistic effect of MXene and Ag, the modified MXene-Ag@Zn anode in a symmetric cell exhibits an ultra-long stable cycle of 4000 h at 1.0 mA cm−2, 1.0 mAh cm−2. The full cell assembled with vanadium-based cathodes can be cycled stably for 3000 cycles at 1.0 A/g. The structural design strategy of this study provides new insights into the protection of Zn anodes in aqueous batteries.