A leveling–shielding dual strategy enabling stable zinc anodes to exhibit ultra-low interfacial impedance

Aqueous zinc-ion batteries have demonstrated great potential for large-scale energy storage, but still suffer from severe dendrites and corrosion problems. Uneven distributions of crystalline planes and passivation layers on the zinc anode are the key factors causing dendrites and corrosion. However, the synergistic construction of uniform crystal planes and shielding layers is still challenging. Herein, we propose a novel leveling-shielding dual strategy to stabilize the zinc anode. The low-melting-point indium (In) layer not only serves as a leveling agent to repair surface defects, but also induces uniform and fast deposition of zinc by exposing a single (101)_In plane on the anode. Besides, the outer ZnF₂ shielding layer can inhibit corrosion and accelerate the de-solvation of Zn(H₂O)₆ ²⁺, which improves the electrochemical reaction kinetics. As a result, the ZnF₂@In@Zn symmetric cell shows an ultra-low interfacial impedance of <10 Ω and a stable cycle life of >2800 h with a low polarization voltage of 21.8 mV at 5 mA cm^-2 and 2 mAh cm^-2, compared with bare Zn (140 h and 75.8 mV). Besides, the ZnF₂@In@Zn//NH₄V₄O₁₀ full cell maintains a high capacity of 112.4 mAh g^-1 with a retention rate of 79.5% after 10 000 cycles at 3 A g^-1. This work provides a novel, effective leveling-shielding dual strategy for interfacial modification of zinc anodes, which can also be applied in other metal anodes.