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

Abstract

Niobium pentoxide (Nb 2 O 5 ) 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 Nb 2 O 5 negative electrode by introducing highly conductive NbO x (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 NbO x layer on the surface of Nb 2 O 5 particles. The NbO x 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 NbO x 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 Nb 2 O 5 .