Constructing a VS4–V2CTx heterojunction interface to realize an ultra-long lifetime and high rate capability in sodium-ion batteries

Abstract

The development of high-energy-density Na-ion batteries (SIBs) is hindered by the lack of a high-capacity anode with fast Na-ion reaction kinetics due to the large Na⁺ radius and slow Na⁺ diffusion kinetics. Herein, a high specific capacity anode is designed by constructing a double vanadium-based compound (VS₄–V₂CT_x) heterostructure composite. The strong rivet structure bridged according to the S–V–C bonding interaction between VS₄ and V₂CT_x unblocks the three-dimensional channel of electron transport and synergistically promotes ion diffusion and charge transport. In addition, the electrochemical reaction kinetics can be enhanced by adjusting the ratio of the vanadium valence state to facilitate electrocatalytic activity at the VS₄–V₂CT_x heterojunction interface. When used as a SIB anode, the VS₄–V₂CT_x composite exhibits excellent ultra-long cycling performance, with a specific discharge capacity of 322 mA h g⁻¹ after 4000 cycles at a large current density of 10 A g⁻¹. All-vanadium SIBs (Na₃V₂(PO₄)₃@C//VS₄–V₂CT_x) are also assembled and showed excellent sodium storage performance with a high reversible capacity of 234 mA h g⁻¹ at 3 A g⁻¹, indicating broad application prospects for vanadium-based sodium storage devices.