High Conductivity and Rate Capability of NaNb₁₃O₃₃ Wadsley–Roth Phase as a Fast‐Charging Li‐Ion Anode

Abstract The synthesis and electrochemical insertion of lithium into the Wadsley–Roth NaNb 13 O 33 phase is studied. Lithium intercalation to form Li x NaNb 13 O 33 reaches a value of up to x~15, between 3.0 and 1.0 V vs. Li + /Li at a slow cycling rate, a capacity of 233 mAh g −1 . Within this voltage window, two sharp peaks and one broad peak are observed in the differential capacity plots of lithium intercalation suggesting multiple two‐phase regions. High Li‐ion conductivity and rate capability was demonstrated. The lithium diffusion constant is about an order of magnitude greater than TiNb 2 O 7 . The average voltage is about 1.6 V and its high‐rate capability makes NaNb 13 O 33 potentially useful as an anode in a fast‐charge Li‐ion battery application.