Ion-sieving MXene flakes with quantum dots enable high plating capacity for dendrite-free Zn anodes

Abstract

The commercial utilization of Zn metal anodes with high plating capacity is significantly hindered by the uncontrolled growth of dendrites and associated side reactions. Herein, a robust artificial ion-sieving MXene flake (MXF)-coating layer, with abundant polar terminated groups, is constructed to regulate the interfacial Zn²⁺ deposition behavior. In particular, the fragmented MXF coupled with in situ generated quantum dots not only has strong Zn affinity to homogenize electric fields but also generates numerous zincophilic sites to reduce nucleation energy, thus securing a uniform dendrite-free surface. Additionally, the porous coating layer with polar groups allows the downward diffusion of Zn²⁺ to achieve bottom-up deposition and repels the excessive free water and anions to prevent parasitic reactions. The ion-sieving effect of MXF is firmly verified in symmetric cells with high areal capacity of 10–40 mAh cm⁻² (1.0 mA cm⁻²) and depth of discharge of 15%–60%. Therefore, the functional MXF-coated anode manifests long-term cycling with 2700 h of stable plating/stripping in Zn||Zn cell. Such rational design of MXF protective layer breaks new ground in developing high plating capacity zinc anodes for practical applications.