Localized nitride strategy to construct interfacial and electronic modulated WO/WN nanoparticles for superior lithium-ion storage.

The interfacial effect is important for the tungsten trioxide (WO)-based anode to achieve superior lithium-ion storage performance. Herein, the interfacial effect was constructed by in-situ surface direct nitridation reaction at 600 ℃ for 30 min of the as-synthesis WO nanoparticles (WO/WN). X-ray photoelectron spectroscopy (XPS) analysis confirms evident chemical interaction between WO and WN via the interfacial covalent bond (WON). This WO/WN anode shows a distinct interfacial effect for an efficient interatomic electron migration. Electrochemical kinetic analysis shows enhanced pseudocapacitance contribution. The galvanostatic intermittent titration technique (GITT) result demonstrates improved charge transfer kinetics. Ex-situ X-ray diffraction (XRD) analysis reveals the reversible oxidation and reduction reaction of the WO/WN anode. The density functional theory (DFT) result shows that the evident interfacial bonding effect can enhance the electrochemical reaction kinetics of the WO/WN anode. The discharge capacity can reach up to 546.9 mA h g at 0.1 A g after 200 cycles. After 2000 cycles, the capacity retention is approximately 85.97 % at 1.0 A g. In addition, the WO/WN full cell (LiFePO/C//WO/WN) demonstrates excellent rate capability and capacity retention ratio. This in-situ surface nitridation strategy is an effective solution for designing an oxide-based anode with good electrochemical performance and beyond.