3D ZnF2–Sn Composite Anode for Ultra-Long-Life Aqueous Zinc-Ion Batteries

Abstract Aqueous zinc-ion batteries hold great promise for large-scale energy storage due to the natural abundance and intrinsic safety of zinc. However, practical application is hindered by uncontrollable dendrite growth and the hydrogen evolution reaction (HER) on the zinc metal anode. Here, we fabricate a three-dimensional (3D) ZnF2–Sn composite zinc metal anode via a one-step method. The outer ZnF2 layer and inner Sn layer synergistically suppress HER and regulate zinc deposition, effectively mitigating dendrite formation. The 3D architecture further accommodates volume variations during long-term cycling, alleviating structural degradation. Consequently, a symmetric cell achieves a cycling life exceeding 2000 h, and an asymmetric cell with a Cu current collector maintains a high Coulombic efficiency over 2000 cycles. More importantly, a Zn–I2 full cell delivers a capacity retention of 94% after 5000 cycles at 1 A g–1. This work provides a rational design strategy for high-performance, long-life zinc metal anodes in aqueous zinc-ion batteries.