In situ nitrogen-doped, defect-induced carbon nanotubes as an efficient anode for sodium-ion batteries

Abstract

Incorporation of heteroatoms and defects in carbonaceous material is well-known approach to improve the electrochemical performance of anode in sodium ion battery (NIB). However, previous works aim either towards heteroatom doped or defect enriched carbon material. Present work is focused on nitrogen-doped, defect induced surface modified carbon nanotubes (MN-BCNT) having synergy of both the effects to improve the electrochemical performance of NIB. Initially, in-situ nitrogen doped carbon nanotubes were grown using scalable, cost-effective and green synthesis technique. In-situ nitrogen doping introduces lattice defects resulting in bamboo shaped carbon nanotubes. Defects were further enriched by opening the ends of tubes and also by length shortening. This structure demonstrates the high capacity of 278 mA h g-1 at a current density of 50 mA g-1, which is more than two times as compared to conventional carbon nanotubes. The improved performance of MN-BCNT is attributed to the improved electrical conductivity due to nitrogen doping and availability of significant active sites owing to length shortening. Moreover, the designed structure shows the good cyclic stability at 200 mA g-1 accompanied with excellent rate capability.