A High-Capacity Gradient Zn Powder Anode for Flexible Zn-Ion Batteries

Zn powder-based anodes are promising for flexible Zn-ion batteries with large-scale production, but the drawbacks such as dendrite growth and side reactions strictly hinder their wide application. Herein, a free-standing Zn powder-based anode with gradient particle size and porosity is facilely constructed for flexible Zn-ion batteries. The gradient design not only optimizes the electric field distribution and the Zn-ion flux but also induces ideal bottom-up deposition and top-down stripping behaviors of Zn, thus suppressing dendrite growth. As a result, the flexible gradient Zn powder anode can be stably cycled for 1250 h at 1 mA cm⁻²/1 mAh cm⁻², and even at high current/capacity of 5 mA cm⁻²/5 mAh cm⁻², it still achieves a long lifespan of 130 h, which outperforms its non-gradient counterparts and most previous results from Zn powder-based anodes. The gradient strategy is expected to inspire the extensive utilization of Zn powder-based anodes for flexible energy storage devices.