Rethinking Thin Sodium‐Metal Anodes for Scalable Manufacturing

The practical development of sodium‐metal batteries requires thin, stable, processable, and scalable sodium‐metal anodes. While thick Na foils remain common in laboratory studies, their excessive sodium inventory can overestimate practical energy‐density and does not represent manufacturable cell architectures. Thin Na anodes, however, are challenging to fabricate because of sodium's extreme softness, ductility, stickiness, low melting point, chemical reactivity, and unstable interfacial behavior. This review examines thin sodium‐metal anodes from a manufacturing perspective, rather than comprehensively revisiting established stabilization strategies. This review first discusses the intrinsic mechanical, chemical, and electrochemical characteristics governing thin‐foil processing and cycling. Composite‐supported sodium, sodium alloying, and artificial interphase engineering are then evaluated in terms of their contribution to processability and structural stability. Particular emphasis is placed on emerging fabrication routes, including roll‐to‐roll processing, melt‐assisted infiltration, vapor deposition, and cryogenic processing, together with their key scale‐up challenges involving atmosphere control, thickness uniformity, inactive mass, interface stability, throughput, and reproducibility. Finally, this review proposes benchmarking criteria and a materials‐to‐manufacturing framework to distinguish demonstrated laboratory capabilities from prospective scale‐up pathways and identify opportunities toward manufacturable, high‐energy sodium‐metal batteries.