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 VO and VSe 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 SeVO 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.