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Antimony（Sb） has high theoretical specific capacity and moderate reaction potential, but poor cycling stability and rate performance caused by large volume expansion and sluggish reaction kinetics limit its development in alkali‐ion batteries. The construction of carbon/Sb composites can solve this problem, but the traditional single carbon composite and poor Sb/carbon interface have limited promotion. Here, under the guidance of theoretical calculations, a strategy of hierarchical double carbon composite is proposed to enhance the performance of Sb anode, and systematically reveal the lithium/sodium ions (Li+/Na+) storage mechanism of Sb in complex composite system. Sb nanoparticles (Sb NPs) are encapsulated in carbon sphere matrix with strong interfacial chemical bond to form the first level composite material, and then the highly conductive and mechanically strong graphene is used as a three‐dimensional skeleton network to connect the first level composite to form the second level composite material. The hierarchical double carbon/Sb composite exhibits excellent rate (228 mAh g−1 @ 20 A g−1) and long cycling performance (373.7 mAh g−1 @ 2 A g−1 after 2200 cycles, capacity retention of 93.1%). This work may expand structural design and interface regulation of Sb/C composites and providing theoretical guidance for metal anodes development. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Antimony-based materials represent promising anode materials for sodium ion batteries (SIBs) owing to their high theoretical capacity, however, the large volume expansion and low ionic conductivity during the electrochemical process prohibit them from reaching their theoretical expectations. In this work, Sb 2 S 3 @C and Sb 2 Se 3 @C nanodots with uniform diameters of 19.0 nm and 20.7 nm were synthesized by H 2 /C thermal reduction and co-sulfurization (selenization) of sodium stibogluconate. Each Sb 2 S 3 and Sb 2 Se 3 nanodot was coated by an interconnecting carbon network with weak graphitization, which further crosslinked together to form a high conductive framework. When applied as anode for SIBs, they exhibited desired sodium storage properties, especially the excellent cycling stability of Sb 2 Se 3 @C nanodots with a reversible capacity of 316.1 mA h g−1 after 100 cycles at 100 mA g−1 and 269.1 mA h g−1 after 200 cycles at 1 A g−1, which was consistent with the calculated result of theoretical volume changes (264% and 246%) and density functional theory (DFT) calculation for both materials during the Na+ intercalation processes, as expected. [Display omitted] • Sb 2 S 3 (Sb 2 S 3) nanodots/C composites have been successfully fabricated. • The volume changes of two materials during the Na+ insertion/deintercalation process have been calculated and analyzed in details. • The satisfactory sodium storage properties are achieved, which is consistent with the result of theoretical calculation. [ABSTRACT FROM AUTHOR]