Defective state regulation of Ru-doped Nb2O5 boosts fast lithium storage.

ABSTRACT

Breaking through the limitations of lithium-ion transmission is imperative for high-power rechargeable batteries. As a promising anode material for fast-charging lithium-ion batteries (LIBs), niobium pentoxide (Nb2O5) has garnered considerable research attention due to its exceptional rate performance, stable lithium storage performance and high safety attributes. Nevertheless, the limited intrinsic conductivity of Nb2O5, coupled with its structural degradation during the cycling process, imposes constraints on its viability as a commercially viable electrode material. Herein, a ruthenium (Ru) doping method is employed to regulate the oxygen defects and the interlayer spacing of the tetragonal Nb2O5 (M-Nb2O5), offering superior reaction kinetics, higher stability for lithium storage sites and more unobstructed lithium-ion transport channels. Ru-doped Nb2O5 (RNO) manifests excellent electrochemical properties, including remarkable rate capacity (166 mAh/g at 80C), reversible capacity (246.98 mAh/g at 0.5C), improved initial Coulombic efficiency (95.77 % compared to 81.44 % of the pure sample) and cycling stability (maintaining a capacity of 113.5 mAh/g at 10C for 2,000 cycles). The enhancement mechanism of Ru doping on the structural stability and ion transport kinetics in tetragonal Nb2O5 is comprehensively elucidated through diverse electrochemical analyses and in-situ techniques.