Structural Distortion in the Wadsley‐Roth Niobium Molybdenum Oxide Phase Triggering Extraordinarily Stable Battery Performance

Abstract Wadsley‐Roth niobium oxide phases have attracted extensive research interest recently as promising battery anodes. We have synthesized the niobium‐molybdenum oxide shear phase (Nb, Mo) 13 O 33 with superior electrochemical Li‐ion storage performance, including an ultralong cycling lifespan of at least 15000 cycles. During electrochemical cycling, a reversible single‐phase solid‐solution reaction with lithiated intermediate solid solutions is demonstrated using in situ X‐ray diffraction, with the valence and short‐range structural changes of the electrode probed by in situ Nb and Mo K‐edge X‐ray absorption spectroscopy. This work reveals that the superior stability of niobium molybdenum oxides is underpinned by changes in octahedral distortion during electrochemical reactions, and we report an in‐depth understanding of how this stabilizes the oxide structure during cycling with implications for future long‐life battery material design.