Inherent Microstructural Engineering: Tailoring Amorphous-Nanocrystalline Composite Films via Ion Beam Technology for Long-Cycle Lithium Metal Batteries.

Lithium metal anode faces formidable challenges from uncontrollable dendrite growth and unstable solid-electrolyte interphase (SEI). Interface engineering of the current collectors (CCs) or lithium anodes presents a viable solution. We propose engineering the intrinsic microstructure of coatings to precisely construct interlayers that are both lithiophilic and possess rapid kinetics. A strategy using ion beam deposition (IBD) technology to craft ZnMgSn films with composite microstructures on commercial Cu CCs and lithium foils is reported. This artificial interphase not only exhibits a strongly lithium adsorption energy, but also significantly reduces the diffusion barrier for lithium atoms, thereby synergistically enabling uniform lithium plating. Crucially, this interphase promotes the in-situ formation of a mechanically robust, bilayer SEI rich in LiF, which can effectively accommodate volume changes during cycling. As a result, the ZnMgSn@Cu CC symmetric cell achieves an ultralong lifespan of over 11000 h. The full cell shows a capacity retention of 85.13% after 130 cycles at 5C. The modified lithium anode maintains over 80% capacity after 620 cycles at 1C. This work not only provides an efficient modification strategy but also offers profound insights into the microscopic design principles for an ideal lithium metal interphase, paving the way for practical lithium metal batteries.