Promoting electrochemical performances of vanadium carbide nanodots via N and P co-doped carbon nanosheets wrapping

High theoretical specific capacity, good electrical conductivity, intrinsically stable metallic nature, excellent thermal stability and corrosion resistance enable vanadium carbide (VC) as a promising anode material for sodium-ion and lithium-ion batteries (SIBs and LIBs). However, drastic structural change during cycling and poor electrochemical kinetic performance both make the application of VC in dilemma. Herein, VC nanodots were successfully embedded in N and P co-doped carbon nanosheets (NPC) via a simple wet chemical process followed by high-temperature calcination. Benefiting from the carbon based conductive network and supporting structure for the rapid ion transport and alleviative volume change in VC, the VC@NPC hybrid exhibits a high reversible capacity (250 mA h g⁻¹ at 0.1 A g⁻¹ after 200 cycles), superior rate capability (88 mA h g⁻¹ at a current density of 5.0 A g⁻¹), and excellent cycle performance (97% capacity retention for 600 cycles at 1.0 A g⁻¹) when evaluated as an anode material for SIBs. Besides, as for LIBs, VC@NPC also shows a high capacity of 532.2 mAh g⁻¹ after 200 cycles at 0.1 A g⁻¹ and 216.6 mAh g⁻¹ after 500 cycles at 1.0 A g⁻¹. This study provides a unique nanocomposite system to achieve a superior electrochemical performance and may pave the way for the further design and construction of novel transition metal carbide anode materials for SIBs, LIBs and other areas.