Yolk-shelled Sb@C nanoconfined nitrogen/sulfur co-doped 3D porous carbon microspheres for sodium-ion battery anode with ultralong high-rate cycling

Sb materials have considered to be one of the most excellent anode materials for sodium ion batteries (SIBs). Developing a Sb-based materials with high-rate long-term cycling durability is highly requisite for boosting their practical application as SIB anodes. In this work, yolk-shell structured Sb@C nanoconfined nitrogen-sulfur co-doped 3D porous carbon microspheres (Sb@NS-3DPCMSs) were prepared via salt-templating directed spray-drying strategy combined with ingenious and continuous high efficiency one-pot multi-step approach. The formation mechanism of the yolk-shell structure was revealed by first-principles simulations for the first time. In the constructed 3D architecture, the robust yolk-shell structure for confining Sb nanocrystals can provide enough void space for effectively buffering the volume expansion of Sb and thus remarkably stabilize the structural integrity of the overall electrode during rapid long-term cycling, while the interconnected empty carbon box with abundant hierarchical pores and high conductivity can facilitate the fast transport of electrons, sodium ions and electrolyte in the whole electrode. Moreover, nitrogen-sulfur co-doping can enhance the intercalation kinetics of sodium ions, and further increase the capacity. As a consequence, the resulting electrode based on the optimized Sb@NS-3DPCMSs exhibits high specific capacity (similar to 540 mA h g(-1) at 100 mA g(-1)), superior rate capability (334 mA h g(-1) at 20 A g(-1)), excellent high-rate cycling capacity retention even at low temperature of 5 degrees C, and ultralong high-rate cycling life (331 mA h g(-1) after 10000 cycles at 20 A g(-1)) as SIB anode.