V2(PO4)O encapsulated into crumpled nitrogen-doped graphene as a high-performance anode material for sodium-ion batteries

Phosphate-based polyanion-structured materials have attracted considerable attention as anode materials in lithium-/sodium-ion batteries due to their stable crystal structure, affordability, and environmental friendliness. V 2 (PO 4 )O was encapsulated into crumpled nitrogen-doped graphene (VPO@N-G) through a facile spray-drying method in which VPO particles were completely encapsulated by N-doped graphene. For the first time, VPO@N-G was explored as an anode material for sodium-ion batteries. The Na + storage behavior of VPO@N-G was systematically investigated at the voltage range of 0.01–3.0 V (versus Na/Na + ). Results indicated that the VPO@N-G anode can deliver a highly reversible discharge capacity of 539 mAh g −1  at 0.05 A g −1 and achieve a highly reversible discharge capacity of 235.9 mAh g −1 even at a high current density of 10 A g −1 . Thus, VPO@N-G can be applied as a high-rate anode material for sodium-ion batteries.