Lithium trapping by excess oxygen inWO3:A first-principles study

Abstract

The process of lithium trapping by excess oxygen atoms in both crystalline and amorphous ${\mathrm{WO}}_{3}$ is studied by first-principles calculations. In both materials, the excess oxygen is incorporated in the bonding network by a peroxide-type bond. In both $c\ensuremath{-}{\mathrm{WO}}_{3}$ and $a\ensuremath{-}{\mathrm{WO}}_{3},$ breaking of this bond makes oxygen states available for the accommodation of the Li electrons. However, only in $a\ensuremath{-}{\mathrm{WO}}_{3}$ is this mechanism accompanied by a strong reduction in total energy as this material has the flexibility to accommodate (incorporate) the extra ${\mathrm{O}}^{2\ensuremath{-}}$ ion.