Superionic Lithium Intercalation through 2 × 2 nm ² Columns in the Crystallographic Shear Phase Nb ₁₈ W ₈ O ₆₉

Nb 18 W 8 O 69 (9Nb 2 O 5 ·8WO 3 ) is the tungsten-rich end-member of the Wadsley–Roth crystallographic shear (cs) structures within the Nb 2 O 5 –WO 3 series. It has the largest block size of any known, stable Wadsley–Roth phase, comprising 5 × 5 units of corner-shared MO 6 octahedra between the shear planes, giving rise to 2 × 2 nm 2 blocks. Rapid lithium intercalation is observed in this new candidate battery material and 7 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 –10 and 10 –12 m 2 ·s –1 . In addition to its promising rate capability, Nb 18 W 8 O 69 adds to our understanding of the large family of high-performance Wadsley–Roth complex metal oxides.