(1 1 0)-Bridged nanoblocks self-assembled VS4 hollow microspheres as sodium-ion battery anode with superior rate capability and long cycling life

Development of three-dimensional self-assembled hollow nanoarchitectures combining functional shells and inner voids is an important approach for realizing high-rate and long-life battery electrodes. As a potential high-performance anode for sodium-ion batteries (SIBs), (1 1 0)-bridged nanoblocks self-assembled VS4 hollow microspheres (PNBH-VS4) are controllably synthesized by a facile one-step hydrothermal method. The (1 1 0)-bridged structure constructs the Na+ conducting channels and e− transfer paths among nano-grains and nanoblocks, and the self-assembled hollow structure presents the double space physical entrapment effect for the excessive volume change of nanoblocks, which synergistically improve the Na+ storage kinetics and structure stability. When employed as an anode for SIBs, PNBH-VS4 electrode exhibits the superior rate capability and long cycling life, outperforming those of the ever-reported VS4-based anode materials. At 0.2, 0.5, 1.0 and 2.0 A g−1, the capacity can reach 629, 564, 428 and 400 mAh g−1 after 250, 200, 350 and 700 cycles, respectively. Even at 5.0 A g−1, the capacity can still stabilize at 309 mAh g−1 after 1000 long cycles. In addition, it is revealed that PNBH-VS4 electrode undertakes the insertion and conversion reaction in the potential range of 0.50–3.00 and 0.05–0.50 V, respectively, where the main capacity contribution originates from the insertion reaction. Meanwhile, PNBH-VS4 electrode exhibits better insertion reversibility at lower current densities and conversion reversibility at higher current densities during cycling, respectively.