Decoding Anode Stability: From Nucleation Kinetics to Pattern‐Guided Flux Control for Long‐Cycling Anode‐Less Sodium Metal Batteries

Abstract Achieving stable operation in sodium metal anode‐less batteries demands a detailed understanding of the earliest stages of metal deposition, a process governed by interfacial energetics, ion‐transport, and local electric field gradients. In this work, the problem is approached from the ground up, beginning with fast scan voltammetry on ultramicroelectrodes to isolate the intrinsic nucleation kinetics of sodium on carbon and copper. These experiments reveal that carbon surfaces not only initiate plating more readily but also support partial reversibility even under high scan‐rate conditions. Building on this, a laser‐patterned current collector is designed to introduce spatially defined sodiophilic domains on copper. This architecture directs a more uniform sodium ion flux and suppresses dendritic instabilities. Real‐time optical imaging and cryogenic electron microscopy confirm that the patterns guide lateral sodium growth and promote a more stable solid electrolyte interphase. At the atomic scale, molecular dynamics simulations reveal how edge defects and chemical affinity influence ion adsorption and mobility. Multiphysics modelling captures how edge‐localized electric fields concentrate ionic flux, validating experimental observations. This integrated strategy enables excellent electrochemical durability, including over 3600 stable half‐cell cycles and 800 full‐cell cycles with >97% capacity retention, offering a clear route to next‐generation, high‐efficiency sodium metal anode‐less batteries.