A Bottom-Up Zincophilic Gradient Design Enabling Long-Cycle-Life Zn Metal Anodes Under High Currents and Capacities.

Abstract

Metal anodes are crucial for achieving high-energy-density electrochemical energy storage. However, their practical performance under high current densities and high areal capacities is hampered by sluggish ion-transport kinetics. This leads to concentration polarization, which promotes surface-localized deposition and results in dendritic "top-growth", ultimately causing cell failure. In this work, we design a bottom-up zincophilic gradient nanofiber mat as a host structure that reverses the deposition pathway. By thermodynamically driving metal ion nucleation preferentially at the host base, this strategy enables uniform bottom-up deposition. As a result, the Zn anode achieves an average Coulombic efficiency of 98.9% for 1972 cycles at a high current density of 20 mA cm^-2. Symmetric cells with this host exhibit exceptional stability, operating for 1095 h at an ultrahigh current density of 50 mA cm^-2 and 1328 h under a high areal capacity of 10 mAh cm^-2, substantially outperforming existing approaches. This work establishes gradient engineering as an effective and widely applicable strategy for enabling long-life metal anodes.