Gradient Interlayer Promotes Highly Stable Zn Metal Anodes for High‐Performance Zn‐Ion Batteries

Abstract Zn metal anodes hold great promise for aqueous batteries due to its high theoretical capacity, suitable redox potential, good compatibility with water‐based electrolytes, and facile accessibility. However, its practical application remains a severe challenge, as Zn dendrite growth and parasitic reactions (e.g., hydrogen evolution reaction (HER), corrosion, and passivation) incur poor cyclic stability. Herein, a unique multi‐filtration‐concentration gradient interlayer integrating a three‐dimensional (3D) structure is constructed to protect the Zn metal anode. Thanks to the rationally engineered interface, this gradient interlayer can filtrate the water molecules in the electrolyte to inhibit HER. Meanwhile, the zincophilic alloy concentrates Zn 2+ ions and homogenizes electric field distribution to ensure uniform Zn deposition. Consequently, with its protection, the symmetric Zn||Zn cell maintains stable cycles for 3330 h with a low overpotential of 14.1 mV. It also endows superior cycle stability of the full‐cells that coupled the Zn anode with MnO 2 and NH 4 V 4 O 10 cathodes under a low N/P ratio, including the Zn||iodine pouch cells. This works provides a facile and industrially applicable method on effectively improving Zn metal anodes for aqueous batteries.