Crystallographic Facet Engineering of LiF for Ultrastable and Superfast Charging Sodium Metal Batteries From –40°C to 60°C

ABSTRACT Sodium metal batteries (SMBs) are promising next‐generation energy storage devices but are plagued by dendritic growth and poor low‐temperature performance, rooted in uncontrolled nucleation and sluggish ion transport. Moving beyond conventional interfacial modifications, we report a crystallographic engineering strategy that precisely controls exposed crystal facets to dictate atomic‐scale electrochemical behavior. Through density functional theory (DFT) screening, we identify the (220) crystal facet of LiF as superior, exhibiting an optimal Na ⁺ adsorption energy (–1.48 eV) and an ultralow diffusion barrier (0.0978 eV), which promotes epitaxial sodium deposition along the (110) plane and significantly reduces nucleation overpotential. Experimentally, we synthesize LiF nanofibers with dominantly exposed (220) facets and construct a composite LiF@Na anode. This design induces a NaF‐rich interphase, markedly enhances desolvation kinetics at the interface, and ensures exceptional interfacial stability. The resulting full cells achieve ultra‐long cycling over 9000 cycles at 50 C with 70% capacity retention and outstanding performance from –40°C to 60°C. This study establishes crystal facet control as a fundamental materials design principle for regulating metal nucleation and interphase chemistry, providing a universal pathway toward high‐energy, durable, and all‐climate metal batteries.