Tungsten Bronze W₃Nb₂O₁₄ Nanorod: The Low-Strain and Preferred Orientation Enables Long-Life for High-Rate Lithium-Ion Storage.

Abstract

Tungsten bronze oxides have emerged as attractive materials for energy storage owing to their fast charge-discharge property. However, the internal weakness of low capacity and short cycling performance impedes their development in wide application. In this work, the tungsten bronze W₃Nb₂O₁₄ nanorods with preferred orientation (001) were prepared by hydrothermal method for the first time. It not only displays high-rate performance but also exhibits high capacity (201 mA h g^-1 at 0.2 C) and long cycling property (80% capacity retention at 50 C after 3000 cycles). Notably, <i>in situ</i> XRD revealed the <i>c</i> evolution frustrates the <i>V</i> increase, and the maximum unit-cell volume expansion is only 2.9% during lithiation/delithiation, reflecting the long cycle performance is benefit from the low strain and preferred orientation. The <i>ex-situ</i> ⁶Li NMR spectra revealed that the lithiation and delithiation present preference based on the size of tunnels in the crystal framework.