Ultra‐Long and Rapid Operating Sodium Metal Batteries Enabled by Multifunctional Polarizable Interface Stabilizer

Abstract Abundant and economical sodium (Na) metal batteries promise superior energy densities compared to lithium‐ion batteries; however, they face commercialization challenges owing to problematic interfacial reactions leading to dendrite formation during cycling. This paper reports the ultra‐long and rapid operation of Na metal batteries enabled by the introduction of a vinylpyrrolidone (VP)‐based multifunctional interface stabilizer in the electrolyte. The VP electrolyte additive provides benefits such as surface flattening, durable solid electrolyte interphase layer formation, preservation of fresh Na, and acceleration of horizontal crystal growth along the (110) plane. Symmetric Na–Na cells with the stabilizer exhibit notably stable operation for over 5 000 cycles at a high current density of 5 mA cm −2 , surpassing previous research. Performance improvement is also demonstrated in a full‐cell configuration with an Na 3 V 2 (PO 4 ) 2 O 2 F cathode. This approach offers a promising solution for achieving performance levels comparable to lithium‐ion batteries in Na metal battery technology.