Niobium-based complex oxides have emerged as promising candidates for high-rate anode materials due to the inherent stability and fast lithium diffusion within some common Nb-oxide structure types as well as the multi-redox capability of niobium (i.e. Nb 5+ to Nb 3+ ). In this work, we explore Nb18W8O69 (9Nb2O5•8WO3) , the tungsten-rich end member of the xNb2O5•yWO3 homologous series. This phase represents the last (i.e., highest tungsten content) of the series to adopt a Wadsley-Roth crystallographic shear (cs) structure (Figure ). With increased tungsten content, the niobium tungsten oxides adopt a bronze-like structure, starting with Nb2WO8. Up to this point, niobium oxide acts a structure-directing agent, in the sense that Nb-rich compounds form cs phases with various block sizes and inter-block connectivities when alloyed with other metal oxides at high temperature. Nb18W8O69 is comprised of the largest (m × n)p blocks of octahedra in any known cs structure with (5 × 5)1 blocks. The subscript p refers to the connectivity of the (m × n) blocks of octahedra where individual blocks isolated by tetrahedra correspond to p = 1, pairs of blocks correspond to p = 2, and chains of blocks without tetrahedra correspond to p = ∞. Many cs structures (and substituted derivatives) have been investigated including binary H-Nb2O5, niobium titanium oxides-TiNb2O7, Ti2Nb10O29, TiNb24O62, and niobium tungsten oxides-Nb12WO33, Nb26W4O77, Nb14W3O44, and Nb16W5O55 1 . These phases vary in block size from (3 × 3) for TiNb2O7 to (4 × 5) for Nb16W5O55 .