Superionic Lithium Intercalation through 2 nm x 2 nm Columns in the Crystallographic Shear Phase Nb18W8O69

Nb₁₈W₈O₆₉ (9Nb₂O₅×8WO₃) is the tungsten-rich end-member of the Wadsley–Roth crystallographic shear (cs) structures within the Nb₂O₅–WO₃ series. It has the largest block size of any known, stable Wadsley–Roth phase, comprising 5 x 5 units of corner-shared MO₆ 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 ⁷Li 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^–10 and 10^–12 m²·s^–1. In addition to its promising rate capability, Nb₁₈W₈O₆₉ adds a piece to the larger picture of our understanding of high-performance Wadsley–Roth complex metal oxides.