Constructing Rich Interfacial Structure by Carbon Dots to Improve the Sodium Storage Capacity of Sb/C Composite

Abstract Designing Sb/carbon composite is an effective strategy to enhance the cycle stability and rate capability of Sb anodes for sodium ion batteries. However, the introduction of carbon often leads to a loss in specific capacity and initial Coulombic efficiency (ICE). In this work, a new perspective is adopted by focusing on improving the “sloping capacity” contribution of carbon (C) in Sb/C composites, rather than solely increasing the platform capacity of Sb as traditionally done. Theoretical predictions indicate that constructing Sb/C composites with high Sb and carbon interfacial areas can provide more Na adsorption sites, thus enhancing the “sloping capacity” of amorphous carbon. Guided by DFT, a rational Sb/C/NSCDs‐2(N) is successfully developed by self‐embedding Sb nanodots into 2D‐amorphous carbon sheets doped with N/S. Sb/C/NSCDs‐2(N) exhibits abundant Sb/carbon interfacial areas and excellent nanoscale effects, demonstrating ideal electrochemical sodium storage performances. Impressively, the Sb/C/NSCDs‐2(N) provides a “sloping capacity” close to 160 mAh g⁻¹. Significantly, owing to the fact that these interfaces and defects are not in direct contact with the electrolyte, the side reaction of electrolyte is effectively inhibited, leading to no decrease of ICE.