Regulating Deposition Behavior of Sodium Ions for Dendrite‐Free Sodium‐Metal Anode

Abstract Constructing dendrite‐free sodium metal anodes with admirable electrochemical performance and long cycle‐life is crucial for the practical application of sodium‐metal batteries (SMBs). One of the feasible methods is to design 3D skeletons with sodiophilicity. Herein, the density functional theory (DFT) calculations indicate that the co‐existence of O and N functional groups on a carbon matrix can imbue strong sodiophilicity, and can regulate the Na deposition behavior to planar extension. Under the guidance of DFT calculation results, robust 3D carbon nanofibers are fabricated with sodiophilic O and N functional groups, which simultaneously facilitates homogeneous Na + distribution and a dendrite‐free construction. The stabilized sodium metal anode achieves an ultra‐long cycle life of 1600 h at 1 mA cm −2 and an overpotential of merely ≈22 mV at 4 mA cm −2 in Na||Na symmetric batteries. Furthermore, superior electrochemical properties are demonstrated in both Na‐O 2 cell and a full sodium ion cell using Na 3 V 2 (PO 4 ) 3 as a cathode, laying the foundation for the next generation high‐performance SMBs.