Submicron interfacial layers for nanoscale control of lithium deposition in surface-engineered current collectors

Lithium metal batteries (LMBs) have garnered considerable attention owing to their high theoretical capacity and low electrochemical potential; however, their practical implementation is hindered by unstable Li plating/stripping and poor interfacial stability. Previous strategies have largely focused on enhancing lithiophilicity or wettability to regulate initial Li deposition, yet they do not necessarily ensure stable long-term cycling. In this study, an interfacial buffer layer was rationally designed for metal-based current collectors to elucidate the distinct contributions of lithiophilicity and wettability to Li deposition behavior. A comparison of representative material systems designed to decouple these effects revealed that interfacial stability, derived from mechanical robustness and adhesion, governs long-term electrochemical performance. Bare Cu induces localized Li nucleation and forms a compositionally heterogeneous and unstable solid electrolyte interphase (SEI), leading to dendritic growth and dead Li accumulation. Conversely, a graphene oxide-poly(vinylidene fluoride)-coated current collector enables uniform Li deposition and promotes the formation of a mechanically robust and chemically homogeneous SEI, improving plating/stripping reversibility. The submicron-thick coating enables effective interfacial control without compromising practical electrode configurations. The resulting system delivers a stable coulombic efficiency of ∼75% over 120 cycles, whereas other configurations exhibit rapid degradation due to interfacial instability. XPS depth profiling revealed the formation of a uniform and lithium fluoride (LiF)-rich SEI with minimal depth-dependent variation, indicating a stabilized interphase. These findings highlight that long-term stability in LMBs is governed by mechanically robust interfacial stability during repeated cycling rather than by initial nucleation behavior, providing clear design guidelines for interface-engineered current collectors.