Coherent Solid-Solution Interface With Near-Zero Lattice Mismatch Enables Stable Zinc Anodes

Aqueous Zn-ion batteries (AZIBs) are attractive for large-scale energy storage owing to their high theoretical capacity, intrinsic safety, and low cost. However, interfacial instability of Zn metal remains a major obstacle, leading to dendritic growth, parasitic reactions, and rapid capacity decay. Here, we introduce a coherent solid-solution interface (SSI) strategy with near-zero lattice mismatch to stabilize the Zn metal anode. The in situ formed SSI exhibits a lattice mismatch of only 0.11% with Zn, enabling coherent Zn growth and suppressing detrimental side reactions. Combined experimental and theoretical analyses reveal that the SSI reduces interfacial polarization, suppresses HER, and promotes uniform lattice-aligned dense Zn deposition. As a result, SSI-Zn delivers stable Zn||Zn symmetric cell cycling for over 9100 h (1 year and 18 days) and achieves Zn||Cu asymmetric cell performance with a Coulombic efficiency (CE) of 99.9% over 10 000 cycles. In full cell configurations, Zn||AC cells and Zn||I₂ cells operate stably for over 120 000 cycles and 17 000 cycles, respectively, with average CE (ACE) values of 99.6% and 99.99%. Furthermore, an anode-free Zn||Br pouch cell operates stably at an areal capacity of 5 mAh cm^-2 with 99.4% ACE, achieving a practical energy density of 61 Wh kg^-1. By coupling near-zero lattice mismatch with interfacial stabilization, this work demonstrates coherent interface engineering as a promising strategy toward high-energy and long-lifespan AZIBs.