Multiscale hierarchical design of bismuth-carbon anodes for ultrafast-charging sodium-ion full battery

Abstract

Bismuth (Bi) is an emerging anode material for sodium-ion batteries (SIBs) owing to favorable attributes of high volumetric capacity, fast internal diffusion of sodium ions, and low redox potential. However, the significant volume expansion exhibited by Bi during charge storage reaction trades off its remarkable energy storage properties. In this study, carbon microtubes coated with bismuth-carbon (CMT@Bi-C) cellular structure were synthesized using a facile and scalable process. The CMT@Bi-C delivers ultrafast charging performance with 78% capacity retention at 200 A g−1 (645 C) and a long cycle life of 82% capacity retention after 5,000 cycles at 10 A g−1. Moreover, full-cell SIBs consisting of CMT@Bi-C anode and Na3V2(PO4)3 cathode demonstrated a high reversible capacity of 105.0 mAh g−1 and an outstanding capacity retention of 90.3 % after 700 cycles at 1 A g−1 (10 C). A multiscale hierarchical design that circumvents the huge volume change in high-capacity anodes has been demonstrated in SIBs with a practical applicability.