Lithium trapping by excess oxygen in WO3:: A first-principles study

The process of lithium trapping by excess oxygen atoms in both crystalline and amorphous WO3 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-WO3 and a-WO3, breaking of this bond makes oxygen states available for the accommodation of the Li electrons. However, only in a-WO3 is this mechanism accompanied by a strong reduction in total energy as this material has the flexibility to accommodate (incorporate) the extra O2- ion.