Modulating d-p orbital hybridization in V₂O₃/Fe₃Se₄@C heterostructure anode for high-performance sodium-ion batteries

Constructing vanadium oxide/metal selenide heterostructure is a promising strategy to enhance the reaction kinetics and structural stability for high-performance sodium-ion batteries (SIBs) anode. However, achieving a uniform and robust heterointerface remains challenging due to the multivalent state transformation of the V and the thermodynamic stability difference between V-O and V-Se bonds. Herein, we design and synthesize the V₂O₃/Fe₃Se₄@C heterostructure via a facile liquid-phase reaction followed by a seleniziation method. The unique coordination environment in a ferric vanadate and the reduction potentials difference between Fe and V cations promote the formation of a well-defined heterointerface. Density functional theory calculations confirm the formation of a built-in electric field at the heterointerface, thereby accelerating the reaction kinetics. The electric field originates from the orbital hybridization, which promotes the formation of a robust Se-V-O bonding configuration. Meanwhile, the carbon coating maintains structural integrity by suppressing volume expansion during cycling. These synergistic effects effectively enhance the overall structural stability of the material. Thus, the prepared V₂O₃/Fe₃Se₄@C anode exhibits exceptional electrochemical performance, delivering a high specific capacity of 378.2 mAh g⁻¹ at 0.5 A g⁻¹ and 308.9 mAh g⁻¹ at 8 A g⁻¹, and retaining a specific capacity of 313.8 mAh g⁻¹ after 2500 cycles at 5 A g⁻¹. This work establishes a new electron orbital modulation strategy for exploring high-performance vanadium oxide-based anode materials for SIBs.