Synergistic S/Se Stoichiometry-Engineered Artificial Interphase for Stable Anode-Free Lithium Metal Batteries

Anode-free lithium metal batteries (AFLMBs) represent a transformative class of next-generation energy storage systems, offering ultrahigh theoretical energy density, cost efficiency, and improved safety. However, their practical deployment is impeded by inhomogeneous lithium deposition on bare current collectors, which triggers severe dendrite growth and unstable solid-electrolyte interphase evolution, thereby accelerating active lithium loss. To address these limitations, we engineer an artificial Li 2 S 0.8 Se 0.2 interface layer on a three-dimensional copper foam via in situ sulfur/selenium coregulation. Systematic optimization identified an optimal S:Se atomic ratio of 4:1, which synergistically enhances ionic conductivity, provides lithiophilic nucleation sites, and stabilizes SEI formation through covalent S–Se bonding. This functional mechanism enables the Li 2 S 0.8 Se 0.2 || Li half-cell to achieve exceptional cycling stability over 900 cycles. Meanwhile, the Li 2 S 0.8 Se 0.2 || LFP full cell maintains remarkable capacity retention (∼80%) and a near-unity average Coulombic efficiency (CE) of 99.86% after 750 cycles at 1C. Most notably, the AFLMBs exhibit 30-fold extended cyclability with 98.9% average CE, establishing a feasible paradigm for stable anode-free batteries through interfacial thermodynamics and kinetics regulation.