Fabrication of nano-solid spherical Nb 2 O 5 /nitrogen-doped carbon composite for high-performance sodium-ion battery anodes

Nano-solid spherical Nb 2 O 5 /nitrogen-doped carbon (NC) composite is obtained by the hydrothermal method followed by a calcination procedure. The Nb 2 O 5 /NC composite exhibits good rate performance and sustainable cyclic stability (144 mAh g −1 at 1000 mAh g −1 upon 2000 charge–discharge cycles) as an anode material in Na-ion batteries (SIBs). The excellent performance of the Nb 2 O 5 /NC composite is attributed to its unique nanosphere structure, in which Nb 2 O 5 nanocrystals embedded in porous NC matrix can restrain agglomeration of Nb 2 O 5 nanocrystals and ensure electrolyte accessibility, and the NC matrix can provide effective active sites and increase ions/electrons transfer. This work offers a new method to fabricate nano-solid spherical Nb 2 O 5 /NC composite with good Na + storage property, which can be extended for synthesizing other metal oxide/NC composite as SIB anode.