Superionic Lithium Intercalation through 2 x 2 nm2 Columns in the Crystallographic Shear Phase Nb18W8O69

Nb18W8O69 (9Nb(2)O(5)center dot 8WO(3)) 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 X 2 nm(2) blocks. Rapid lithium intercalation is observed in this new candidate battery material and Li-7 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, Nb18W8O69 adds to our understanding of the large family of high- performance Wadsley-Roth complex metal oxides.