Metastable V2O3 embedded in 2D N-doped carbon facilitates ion transport for stable and ultrafast sodium-ion storage

V 2 O 3 is a promising candidate for sodium-ion batteries (SIBs) anode. Compared with common rhombohedral V 2 O 3 , cubic V 2 O 3 is a unique metastable phase with ordered oxygen vacancies and high energy state, but lacks study in the field of electrochemical energy storage. Herein, a metastable cubic V 2 O 3 embedded in N-doped carbon nanosheets (c-V 2 O 3 @NC) is synthesized by a simple molten salt method with urea assisted. Ab initio molecular dynamics calculations demonstrate that cubic V 2 O 3 possesses reduced Na + diffusion activation energy. Benefiting from the novel metastable structure and multiple modifications, the c-V 2 O 3 @NC shows enhanced ion diffusion kinetics, robust structure and improved conductivity. As a consequence, the c-V 2 O 3 @NC exhibits high specific capacity, ultralong cycle life and ultrahigh rate capability (274 mAh g −1 even after 3000 cycles at 5 A g −1 ) as anode material for SIBs. This work shows a feasible synthesis and synchronous modification for metastable materials to electrical energy storage applications.