SnO2 particles anchored on N-doped graphene surface as sodium-ion battery anode with enhanced electrochemical capability

The small-size SnO2 particles uniformly dispersed on the nitrogen doping graphene nanocomposites (SnO2-N-GNS) have been successfully synthesized by a mild hydrothermal method with the precursors of graphene oxide, urea and SnCl4.5H2O. The phase (XRD, EDX and XPS) and morphology (SEM, TEM) analysis further confirm the obtained products. When the composite served as anode material in sodium ion batteries (SIBs), it delivers superior sodium storage performance with reversible discharge capacity of 294.4 mAh g−1 at a current density of 50 mA g−1 in the voltage range from 0.01-3 V after 50 discharge/charge cycles, which is much higher than that of SnO2-GNS (182.9 mAh g−1) and N-GNS (114.9 mAh g−1). Besides, the SnO2-N-GNS electrode also exhibits admirable rate stability with the discharge capacity of 206 mAh g−1 even at 800 mA g−1. More importantly, the SnO2-N-GNS shows lower internal resistance and larger sodium-ion diffusion coefficient. These enhanced electrochemical performances of SnO2-N-GNS are due to the N-doping defects and the homogeneous dispersion of SnO2 particles.