Nanostructured Nb2O5 Polymorphs by Electrospinning for Rechargeable Lithium Batteries

Polymorphs of 1D nanostructures of niobium pentoxide (Nb2O5) are synthesized by electrospinning. Pseudohexagonal (H-Nb2O5), orthorhombic (O-Nb2O5), and monoclinic (M-Nb2O5) structures of Nb2O5 are developed in this study by appropriate heat treatment. Morphological, structural, and electrochemical properties of these nanofibrous polymorphs are studied in detail. The H- and O- phases maintain the usual fibrous morphology, whereas the M- phase adopted a distorted nugget structure. These phases are evaluated for their application as cathode for lithium batteries. The M-Nb2O5 exhibits the highest capacity and better capacity retention compared to the other phases. The M-Nb2O5 delivers a specific capacity of 242(+/- 3) and 218(+/- 3) mAhg(-1), cycled at a current of 50 mAg(-1) in the voltage range, 1.0-2.6 V versus Li/Li+ at the end of second and 25th cycle, respectively. The electrospun M-Nb2O5 nuggets-based battery performs better than its particle/nanofiber counterpart and could be a cathode material of choice for 2 V due to the commercial viability of the electrospinning process and characteristics of the batteries developed herewith.