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

Abstract Intertwined nitrogen‐doped carbon nanotubes (N‐CNTs) are prepared by using a hard‐template method with V 2 O 5 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.