Porous ZnP matrix for long-lifespan and dendrite-free Zn metal anodes

Abstract

The reversibility of Zn plating/stripping during cycling is adversely affected by dendritic growth, electrochemical corrosion, surface passivation, and hydrogen generation on the Zn anodes for rechargeable aqueous zinc ion batteries (ZIBs). Herein, through an ordinary anodic etching process, a uniform porous ZnP matrix protective layer was created on the Zn foil (Zn@ZnP). The large and accessible specific surface area of the prepared Zn@ZnP can facilitate contact with the electrolyte, accelerating the migration and enhancing the desolvation of Zn²⁺, effectively enhancing the Zn deposition kinetics. According to studies from scanning electron microscopy (SEM) and multiscale optical microscopy, the Zn@ZnP electrode effectively inhibits the growth of dendrites with excellent Zn plating/stripping reversibility. In consequence, the symmetric cell with the Zn@ZnP electrodes displays a long-term cycle life of over 1260 h at 10  mA  cm⁻². The full cell, consisting of Zn@ZnP anodes and MnO₂-based cathode, demonstrated a high discharge capacity of 145 mAh g⁻¹ after cycling 500 times at the current density of 1000 mA  g⁻¹. A scalable method for designing a homogeneous anode protection layer enables dendrite-free zinc metal anodes, paving the way for interface modification of other metal anodes.