Intertwined Nitrogen-Doped Carbon Nanotubes for High-Rate and Long-Life Sodium-Ion Battery Anodes

Intertwined nitrogen-doped carbon nanotubes (N-CNTs) are prepared by using a hard-template method with V2O5 nanowires as the hard template and dopamine as the carbon and nitrogen source, and the N-CNTs are characterized in details. As anodes in sodium-ion batteries (SIBs), the N-CNTs deliver a capacity of 179.1 mAh g−1 at 0.2 A g−1, and a capacity of 91.7 mAh g−1 is maintained even at 10 A g−1. After cycling for 1000 cycles at 1 and 5 A g−1, the capacity of the N-CNTs is retained at 125.5 and 104.2 mAh g−1, respectively. The excellent electrochemical performance in terms of rate capability and lifespan of the N-CNTs can be attributed to the synergistic effects of the intertwined one-dimensional hollow structure with hierarchical pores, extrinsic nitrogen content, and large interlayer distance of the graphene sheets.