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

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 WNbO 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 at 0.2 C) and long cycling property (80% capacity retention at 50 C after 3000 cycles). Notably, XRD revealed the evolution frustrates the 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 Li NMR spectra revealed that the lithiation and delithiation present preference based on the size of tunnels in the crystal framework.