Rapid Microwave Preparation of AlNb11O29 and Ti2Nb10O29 Wadsley–Roth Lithium–Ion Anode Compounds from Parent Oxides

Niobium–based Wadsley–Roth oxides have recently attracted attention as promising anode materials for lithium-ion batteries, providing high charging and discharging rates and cycling stability. The higher operating potential of Wadsley–Roth oxide anodes, while impacting the overall energy density, reduces the risk of dendrite formation, making them safer at high power densities. We present the rapid preparation of two Wadsley–Roth oxide compounds, AlNb11O29 and Ti2Nb10O29, by a microwave-assisted preparation method in under 10 min starting from oxide materials, and heating in open crucibles. No further processing is required to make effective electrode materials from these compounds other than grinding with the usual conducting carbon and binder. High-resolution synchrotron X-ray diffraction and scanning electron microscopy are employed to understand the impact of rapid preparation on the structure and morphology. Excellent electrochemical performance is achieved, with reversible capacities of up to 250 mAh g–1 with high capacity retention over 100 cycles and fast-charging rates up to 10C without much loss of capacity. The materials reported here are compared to reports from the literature. Despite the very similar structures and compositions, AlNb11O29 is found to be less effective as an anode material than Ti2Nb10O29, and in this work, we delve into possible reasons for this.