Facet-Engineered ZnO as an Interfacial Regulator for Stable Lithium Metal Anodes

Interfacial instability remains the primary obstacle to realizing high-energy Li-metal batteries (LMBs). Here, we demonstrate that ZnO can function not as a conventional anode material but as a facet-engineered interfacial regulator that stabilizes Li-metal deposition. Using electrothermal-wave (ETW) processing, we precisely modulate atomic diffusion kinetics to tailor the crystal facet orientation and morphology of ZnO nanostructures on carbon fibers. This controllable platform enables decoupling the facet- and morphology-dependent effects on interfacial stability. Mechanistic analyses reveal that the semipolar (101) facet forms a conductive Li-Zn interface that promotes uniform Li nucleation and enables long-term plating/stripping stability (>800 h), whereas the polar (002) facet generates an insulating Li₂O-rich layer that impedes charge transfer. Concurrently, a 2D planar morphology enhances the electrochemically active surface area and exchange current density, yielding more favorable Li plating kinetics than 3D architectures. The optimized ZnO@CF electrode, integrating the (101)-dominant facet and planar configuration, delivers stable reversibility in half-cells and retains 80 % capacity over 200 cycles at 0.5 C in full-cell pairing with a commercial NCM523 cathode. This study establishes a design framework where facet-dependent interfacial reactivity and morphology-dependent kinetic regulation act synergistically to stabilize reactive metal interfaces, offering a new paradigm for durable and efficient LMB anodes.