Sodium ion batteries (SIBs) have attracted increasing attentions as promising alternatives to lithium ion batteries (LIBs). Herein, we design and synthesize ultrasmall MnO nanoparticles (∼4 nm) supported on nitrogen-doped carbon nanotubes (NDCT@MnO) as promising anode materials of SIBs. It is revealed that the carbonization temperature can greatly influence the structural features and thus the Na-storage behavior of the NDCT@MnO nanocomposites. The synergetic interaction between MnO and NDCT in the NDCT@MnO nanocomposites provides high rate capability and long-term cycling life due to high surface area, electrical conductivity, enhanced diffusion rate of Na+ ions, and prevented agglomeration and high stability of MnO nanoparticles. The resulting SIBs provide a high reversible specific capacity of 709 mAh g-1 at a current density of 0.1 A g-1 and a high capacity of 536 mAh g-1 almost without loss after 250 cycles at 0.2 A g-1. Even at a high current density of 5 A g-1, a capacity of 273 mAh g-1 can be maintained after 3000 cycles.
Keywords: MnO nanoparticle; Sodium ion battery; anode; electrode reactions; nitrogen-doped carbon nanotube.