Inducing a Conductive Surface Layer on Nb₂O₅ via Argon-Ion Bombardment: Enhanced Electrochemical Performance for Li-Ion Batteries

Abstract

Niobium pentoxide (Nb₂O₅) is in the limelight as a negative electrode material for advanced electrical energy storage devices owing to its unique pseudocapacitive behavior. However, its intrinsic poor electronic conductivity restricts its electrochemical performance. In this study, argon-ion bombardment is employed to enhance the interfacial properties of the Nb₂O₅ negative electrode by introducing highly conductive NbOx (1 ≤ x ≤ 2) species on the electrode surface. Detailed analysis by X-ray photoelectron spectroscopy (XPS) and transition electron microscopy (TEM) reveals that introducing the NbOx layer on the surface of Nb2O5 particles. The NbOx surface architecture fosters improvements in the electrochemical performance of the argon-ion bombarded electrode, exhibiting a higher reversible capacity of 211 mAh g⁻¹ than that of pristine electrodes (138 mAh g⁻¹). Electrochemical impedance spectroscopic analysis reveals that introducing the surface NbOx layer promotes charge transfer at the electrode surface and breaks the limitations of charge transfer resistance. The result provides a pathway to enhance the intrinsic shortness of conductivity and to establish surface modification simultaneously via a simple argon-ion bombardment method, thus achieving the improved electrochemical performance of Nb₂O₅.