New Anode Material for Lithium-Ion Batteries: Aluminum Niobate (AlNb₁₁O₂₉)

This paper describes the syntheses and electrochemical properties of a new niobate compound, aluminum niobate (AlNb₁₁O₂₉), for Li⁺ storage. AlNb₁₁O₂₉-microsized particles and nanowires were synthesized based on the solid-state reaction and solvothermal methods, respectively. In situ X-ray diffraction results confirmed the intercalating mechanism of Li⁺ in AlNb₁₁O₂₉ and revealed its high structural stability against cycling. The AlNb₁₁O₂₉ nanowires with a novel bamboo-like morphology afforded a large interfacial area and short charge transport pathways, thus leading to the observed excellent electrochemical properties, including high reversible Li⁺-storage capacity (266 mA h g^-1), safe operating potential (around 1.68 V), and high initial Coulombic efficiency (93.3%) at 0.1 C. At a very high rate (10 C), the AlNb₁₁O₂₉ nanowires still exhibited a capacity as high as 192 mA h g^-1, indicating their good rate capability. In addition, at 10 C, 96.3% capacity was retained over 500 cycles, indicating superior cycling stability. A full cell fabricated with AlNb₁₁O₂₉ nanowires as the anode and LiNi_0.5Mn_1.5O₄ microparticles as the cathode delivered a high energy density of 390 W h kg^-1 at 0.1 C. This work suggests that the AlNb₁₁O₂₉ nanowires hold a great promise for the development of high-performance lithium-ion batteries for large-scale energy-storage applications.