Synthesis and performance of micron-sized hexagonal W0.025Nb1.97O5 for high-rate lithium-ion batteries

Abstract

Niobium-based oxides have been considered as one of the prospective anode materials for Lithium-ion batteries (LIBs) on account of their high theoretical specific capacity, small volume change, and high safety. Particularly, the metastable bronze phase T-Nb2O5, with open Nb–O pentagonal bipyramids interconnected channels, shows outstanding intercalation pseudocapacitance. However, they generally suffer from unsatisfactory electronic conductivity. Here, micron-sized hexagonal orthorhombic W0·025Nb1·97O5 has been prepared with selenide as a template. The phases and crystal structure have been maintained after doping. The W6+ doping could improve the electrical conductivity via charge redistribution. The density functional theory (DFT) calculations manifest that production of impurity bands due to W6+ doping led to improved electrical conductivities. When acting as electrode materials for LIBs, W0·025Nb1·97O5 shows high-rate capacity (139.9 mAh g−1 at 20 C) and outstanding cycling performance (126.4 mAh g−1 at 5 C after 1000 cycles). We put forward a novel W6+ doping T-Nb2O5, and this strategy may be utilized as a universal solution for other niobium-based oxides electrode materials.