Electron-donor modulated built-in electric fields in Ni₂P/MoS₂ Heterostructures for accelerated sodium storage...

Heterostructure engineering, particularly involving transition metal sulfides (TMSs) such as MoS₂, has emerged as a promising strategy for developing advanced anodes. However, the intrinsically large band gap and limited electronic conductivity restrict its electrochemical performance, which can be effectively modulated by introducing metallic components. Herein, we successfully constructed the Ni₂P/MoS₂@NC heterostructure, in which Ni₂P acts as an electron donor for enhanced conductivity of MoS₂ based anode. Prior density functional theory (DFT) calculations confirm that the built-in electric fields provide abundant Na⁺ adsorption sites, reducing migration energy barriers and accelerating reaction kinetics. Furthermore, the Ni₂P/MoS₂@NC-2 electrode delivers an impressive reversible specific capacity of 484.5 mAh g^-1 after 200 cycles at 0.1 A g^-1, while maintaining excellent structural durability during prolonged cycling (340.3 mAh g^-1 after 1000 cycles at 1.0 A g^-1). Comprehensive in/ex-situ characterizations combined with relaxation time distribution (DRT) analysis further explore sodium storage mechanism and enhanced diffusion kinetics. Notably, the assembled full cell (Ni₂P/MoS₂@NC-2//Na₃V₂(PO₄)₃) also demonstrates excellent electrochemical performance. It is expected to offer valuable guidance for TMSs/transition metal phosphides (TMPs) heterostructure anodes for sodium-ion batteries.