Pomegranate-like structured Nb2O5/Carbon@N-doped carbon composites as ultrastable anode for advanced sodium/potassium-ion batteries

The distinctive pomegranate-like Nb 2 O 5 /Carbon@ N -doped carbon (Nb 2 O 5 /C@NC) composites are fabricated using hydrothermal method integrated with nitrogen doped carbon coating procedure. For the SIBs anode, the Nb 2 O 5 /C@NC composites present superior rate character and sustainable capacity (117 mAh g −1 upon 1000 cycles at 5 A g −1 ). The in-situ X-ray diffraction (XRD) is utilized to research its sodium storage mechanism. Furthermore, for PIBs, the Nb 2 O 5 /C@NC composites present sustainable capacity (81 mAh g −1 upon 1000 cycles at 1 A g −1 ). The outstanding performance of Nb 2 O 5 /C@NC composites is ascribed to its unique architecture, in which Nb 2 O 5 nanocrystals embedded in porous carbon can restrain agglomeration of Nb 2 O 5 nanocrystals, enhance electron/ion diffusion kinetics , and ensure electrolyte accessibility, and moreover, NC shell layer can provide effective active sites and further increase ions/electrons transfer.