Lithiation kinetics and performance of Nb18Mo16O93 anode materials based on tetragonal tungsten-bronze structures

Abstract

In lithium-ion batteries (LIBs) anode materials, Nb2O5 has a higher specific capacity and working potential than graphite, but its low conductivity and the problem of asynchronous phase transition in the reaction limit the specific capacity as well as the cycling performance of the material. In this study, Nb18Mo16O93 LIBs anode materials with tetragonal tungsten bronze (TTB) structure were successfully synthesized by combining ball milling and calcination method, using MoO3 and Nb2O5 as raw materials. The introduction of Mo atoms has led to the formation of a new material that solves the problem of low electrical conductivity of Nb2O5. Meanwhile, the Nb18Mo16O93 material forms three kinds of channels to promote Li+ transport, namely pentagonal, square channel and triangular, due to its special TTB structure. In addition, the rod-like morphology of the Nb18Mo16O93 material provides a larger contact area between the electrolyte and the electrode material, which improves the adsorption and diffusion efficiency of lithium ions. Nb18Mo16O93 as an anode material maintained a specific capacity of 692 mAh g−1 after 300 cycles at 0.1 A g−1 and 75.5 mAh g−1 after 3000 cycles at a high current of 5 A g−1. The preparation of Nb18Mo16O93 provides a new direction to solve the shortcomings of Nb2O5.