Carbon-encapsulated Sb-based nanotubes enable advanced lithium storage anode

Antimony-based anodes, due to their high theoretical capacity, receive significant interest, but their further application in LIBs has been hindered by the large volumetric variation during lithiation/delithiation. To identify potential candidates with superior stability, COMSOL Multiphysics simulations are performed to analyze the voltage changes, lithium-ion concentrations, and stress distribution of solid rod, single-layer hollow tube, and dual-layer hollow tube model. It is obvious that the battery voltage changes and lithium-ion concentrations of these models are virtually the same. However, the stress distribution of the first two models presents the feature of small stress in the middle and large stress near the ends, while for the dual-layer hollow tube model, the closer to the end, the smaller the stress value is instead. In the meantime, the dual-layer hollow tube can effectively decrease the stress of the electrode more than 30 %. Herein, inspired by the theoretical prediction results, a carbon-encapsulated Sb nanotube (Sb@C) anode material is designed and fabricated by a simple hydrothermal method and subsequent treatments. Besides the alleviation of vast expansion of the Sb volume, the small pores of the encapsulated carbon layer provided more channels for Li + transport, which boosted the electrochemical performance of the Sb@C nanotube electrode. Consequently, under 0.1 A g −1 after 1000 cycles, the cell with the Sb@C nanotube anode retains the discharged capacity is 226.1 mAh g −1 with 99.7 % CE indicating good cycling stability. This study provides a fundamental insight into Sb-based electrodes and offers meaningful guidance for designing high-capacity and high-performance Sb-based nanotube anodes for lithium storage and beyond.