Designing a Multifunctional Lithium Metal Interface with “Solvent Capture–Desolvation Promotion–Ion Guidance” via Spin State Engineering of Spinel Oxides

Abstract Lithium metal is regarded as the ultimate anode for high‐energy‐density batteries due to its ultra‐high theoretical specific capacity (3860 mAh g −1 ) and lowest redox potential (−3.04 V vs standard hydrogen electrode). However, lithium dendrite growth remains a major challenge. In this study, a multifunctional interfacial layer is constructed using Fe 3+ ‐doped spinel oxide anchored on carbon nanofibers (CoMnFe@CNF). Through Fe 3+ ‐mediated cation regulation, the spin state of Co 3+ Tetrahedral (Td) is altered to enable directional solvent capture, while Mn 3+ Octahedral (Oh) sites promoted electron delocalization for enhanced desolvation and ion guidance. Density Functional Theory revealed spin‐reconstructed Co 3+ (Oh) sites increased Li⁺ adsorption energy from −0.96 to −3.06 eV via strong Lewis acid–base interactions. Concurrently, Mn 3+ ‐induced electron delocalization accelerated desolvation and optimized ion transport pathways. This enabled a synergistic mechanism of “solvent capture–desolvation promotion–ion guidance” to effectively suppress dendrite formation. The modified lithium anode delivered stable cycling over 2000 h, and demonstrated excellent performance in full cells. This work offers a new strategy for stabilizing lithium metal anodes via spin‐state engineering of spinel oxides, advancing practical lithium metal battery applications.