Superionic Lithium Intercalation through 2 nm x 2 nm Columns in the Crystallographic Shear Phase Nb18W8O69
<p>Nb<sub>18</sub>W<sub>8</sub>O<sub>69</sub> (9Nb<sub>2</sub>O<sub>5</sub>×8WO<sub>3</sub>) is the tungsten-rich end-member of the Wadsley–Roth crystallographic shear (<i>cs</i>) structures within the Nb<sub>2</sub>O<sub>5</sub>–WO<sub>3</sub> series. It has the largest block size of any known, stable Wadsley–Roth phase, comprising 5 x 5 units of corner-shared MO<sub>6</sub> octahedra between the shear planes, giving rise to 2 nm x 2 nm blocks. Rapid lithium intercalation is observed in this new candidate battery material and <sup>7</sup>Li pulsed field gradient nuclear magnetic resonance spectroscopy – measured in a battery electrode for the first time at room temperature – reveals superionic lithium conductivity with Li diffusivities at 298 K predominantly between 10<sup>–10</sup> and 10<sup>–12</sup> m<sup>2</sup>·s<sup>–1</sup>. In addition to its promising rate capability, Nb<sub>18</sub>W<sub>8</sub>O<sub>69</sub> adds a piece to the larger picture of our understanding of high-performance Wadsley–Roth complex metal oxides.</p>