Electrochemically Self-Adapting Interlayer for Controlled Zn²⁺ Transport in Aqueous Zn-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) are attractive for grid-scale energy storage owing to their intrinsic safety and low cost. Yet their practical deployment is impeded by Zn dendrites and persistent interfacial instability, which are closely linked to nonuniform Zn²⁺ flux at the Zn anode-separator interface. Herein, we engineer a titanium nitride (TiN) interlayer at this interface to regulate Zn²⁺ transport and homogenize ion flux. In situ synchrotron radiation X-ray diffraction (SRXRD) reveals an electrochemical-induced crystallographic reorientation of TiN from a (111)-preferred texture to (200). Density functional theory (DFT) calculations further show that TiN (200) has a lower surface energy, weaker Zn²⁺ adsorption, and more favorable Zn²⁺ migration pathways than TiN (111), enabling a dynamically optimized, electrochemically self-adaptive interlayer that progressively equalizes interfacial Zn²⁺ flux and improves Zn plating/stripping reversibility. As a result, Zn//Zn symmetric cells deliver stable cycling for over 1100 h, while MnO₂-based full cells exhibit improved rate capability and long-term capacity retention. This work highlights crystallography-driven interlayer adaptivity as a general strategy for constructing stable interfaces toward safe, durable, and scalable aqueous Zn-ion batteries.