The sodium (Na) metal anode suffers from uncontrolled dendrite growth and an unstable solid-electrolyte interphase (SEI), especially when high areal capacity is required. Herein, we have developed a multifunctional Na host, nitrogen-doped carbon shells anchored with antimony single atoms (SbSA-NC). The host is prepared via vacuum pyrolysis of polypyrrole-coated Sb2O3, during which sublimated Sb2O3 is partially captured by the carbonized polymer shells in the form of single atoms. During multiscale monitoring and electrochemical measurements, SbSA-NC demonstrates the ability of inhibiting dendrite growth, reducing nucleation overpotential, and enabling the half-cells to achieve an average Coulombic efficiency above 99.9% for over 2000 cycles. The excellent performance of SbSA-NC, as revealed by Cryo-TEM analysis, is correlated with the conformal and uniform SEI with abundant NaF or the rather good mechanical and chemical stability of the SEI. When paired with Na3V2(PO4)3 cathodes, full cells achieve 84% capacity retention after 5000 cycles at 5 C.
Keywords: Cryo-TEM; antimony single atoms; sodium metal host; solid−electrolyte interphase; vacuum pyrolysis.