Heteroatom doped rGO encapsulated Nb2O5 composite as high-performance anodes for Li-ion batteries

Nb2O5 can be viewed as one of the most potential high-rate anodes for Li-ion batteries (LIBs) in terms of its Li intercalation mechanism. However, inherent low electron transfer capability of Nb2O5 has restricted its potential application in high-power equipment. Herein, the nitrogen-doped rGO and phosphorus-doped rGO encapsulated Nb2O5 (Nb2O5@N-rGO and Nb2O5@P-rGO) composites are designed and synthesized through a hydrothermal method followed by a non-contact sintering treatment. As anodes for the LIBs, the charge/discharge capability and lithium intercalation mechanism of the synthesized samples are explored. Nb2O5@N-rGO composite maintains a discharge capability of 97.8 mA h g-1 even under 20C, while Nb2O5@P-rGO composite exhibits superior cycling stability, with a capacity loss ratio of 7.24 % over 100 cycles under 0.5 C, much better than those of pure Nb2O5 and Nb2O5@rGO. The advanced charge/discharge properties can be attributed to the heteroatom doping of nitrogen/phosphorus elements in rGO, which can bring in defects and dislocations and provide more Li-storage active sites and fast electron transport channels, further boosting the charge transport speed in the doped materials. This work not only provides the highly promising anode materials for LIBs, but also opens up a feasible way to prepare excellent electrode materials for high-power batteries.