Development of tungsten–molybdenum-based multicomponent complex oxides

Abstract

A multicomponent complex oxide, (W_0.41Mo_0.32V_0.19Ta_0.08)₅O₁₄, with a Mo₅O₁₄-type crystal structure and needle-like particles has been newly observed by scanning transmission electron microscopy (STEM), which confirmed that the four cations were homogeneously distributed in each particle. Each cation of this complex oxide seems to have a certain solid solution range for each valence. In this study, complex oxides with the same type of crystal structure could not be confirmed in a quaternary system or lower-order systems, namely, W–Mo–O, W–V–O and W–Mo–V–O. It is considered that the complex oxide was stabilized by simultaneously adding vanadium and tantalum. In addition, it was shown for the first time that this material has a Mo₅O₁₄-type structure with stable Li-ion battery characteristics. The initial discharge capacity was 161 mAh g⁻¹ (880 mAh cm⁻³) in the range of 1.55–3 V. The capacity was nearly constant and stable above 80 % even after 100 charge/discharge cycles.