Template-free synthesis of hierarchical hollow urchin-like fluorine-doped Nb2O5 microspheres for fast and stable lithium-ion storage

Abstract

Nb2O5 has become a promising fast-charging anode for lithium-ion batteries (LIBs) owing to its open framework structure, safe operating potential, and pseudocapacitance properties. However, its poor electronic conductivity can lead to sluggish reaction kinetics and severe capacity decay, which restricts its commercial application. Herein, hierarchical hollow urchin-like F-doped Nb2O5 microspheres are successfully produced using a template-free hydrothermal technique for the first time. The resulting F-doped Nb2O5 anode delivers exceptional electrochemical performance, including superior rate capability (148 mAh g−1 at 20 C) and long-term cyclic stability (77% capacity retention after 500 cycles at 20 C). Moreover, a full cell assembled with F-doped Nb2O5 and commercial LiNi0.5Mn0.3Co0.2O2 demonstrates high capacity along with exceptional rate performance. The remarkable electrochemical capabilities of F-doped Nb2O5 can be ascribed to the combined advantages of hollow urchin-like structure and F-doping, which enhance electron/ion diffusion kinetics, accommodate volume expansion, and improve electronic conductivity.