Gradient Distribution of Zincophilic Sites for Stable Aqueous Zinc‐Based Flow Batteries with High Capacity

Abstract Current collectors, as reaction sites, play a crucial role in influencing various electrochemical performances in emerging cost‐effective zinc‐based flow batteries (Zn‐based FBs). 3D carbon felts (CF) are commonly used but lack effectiveness in improving Zn metal plating/stripping. Here, a current collector with gravity‐induced gradient copper nanoparticles (CF‐G‐Cu NPs) is developed, integrating gradient conductivity and zincophilicity to regulate Zn deposition and suppress side reactions. The CF‐G‐Cu NPs electrode modulates Zn nucleation and growth via the zincophilic Cu/CuZn₅ alloy has been confirmed by density functional theory (DFT) calculations. Finite element simulation demonstrates the gradient internal structure effectively optimizes the local electric/current field distribution to regulate the Zn²⁺ flux, improving bottom‐up plating behavior for Zn metal and mitigating top‐surface dendrite growth. As a result, Zn‐based asymmetrical FBs with CF‐G‐Cu NPs electrodes achieve an areal capacity of 30 mAh cm⁻² over 640 h with Coulombic efficiency of 99.5% at 40 mA cm⁻². The integrated Zn‐Iodide FBs exhibit a competitive long‐term lifespan of 2910 h (5800 cycles) with low energy efficiency decay of 0.062% per cycle and high cumulative capacity of 112800 mAh cm⁻² at a high current density of 100 mA cm⁻². This gradient distribution strategy offers a simple mode for developing Zn‐based FB systems.