Bottom‐Up Confined Synthesis of Nanorod‐in‐Nanotube Structured Sb@N‐C for Durable Lithium and Sodium Storage

Abstract Antimony (Sb) has emerged as an attractive anode material for both lithium and sodium ion batteries due to its high theoretical capacity of 660 mA h g −1 . In this work, a novel peapod‐like N‐doped carbon hollow nanotube encapsulated Sb nanorod composite, the so‐called nanorod‐in‐nanotube structured Sb@N‐C, via a bottom‐up confinement approach is designed and fabricated. The N‐doped‐carbon coating and thermal‐reduction process is monitored by in situ high‐temperature X‐ray diffraction characterization. Due to its advanced structural merits, such as sufficient N‐doping, 1D conductive carbon coating, and substantial inner void space, the Sb@N‐C demonstrates superior lithium/sodium storage performance. For lithium storage, the Sb@N‐C exhibits a high reversible capacity (650.8 mA h g −1 at 0.2 A g −1 ), excellent long‐term cycling stability (a capacity decay of only 0.022% per cycle for 3000 cycles at 2 A g −1 ), and ultrahigh rate capability (343.3 mA h g −1 at 20 A g −1 ). For sodium storage, the Sb@N‐C nanocomposite displays the best long‐term cycle performance among the reported Sb‐based anode materials (a capacity of 345.6 mA h g −1 after 3000 cycles at 2 A g −1 ) and an impressive rate capability of up to 10 A g −1 . The results demonstrate that the Sb@N‐C nanocomposite is a promising anode material for high‐performance lithium/sodium storage.