The Effect of Crystallinity of Nanoporous WO₃ on the Intercalation and Deintercalation of Li⁺

Abstract

Nanoporous anodic WO3 was annealed at three different times of 1h, 2h, and 3h at a constant temperature of 500oC. This was to investigate the intercalation and deintercalation behaviour of Li+ in this annealed nanoporous oxide. The as-anodised WO3 is amorphous and after annealing, monoclinic WO3 was observed with much higher degree of crystallinity when the time of annealing was increased from 1h to 3h. By electrodiffusion of Li+ in the nanoporous structure, an ion exchange between fully oxidized states (W6+) which is the octahedral coordination dominates (WO6) and Li+ could happen. This causes changing of the colour of the yellowish WO3 to bluish WO3.Li2O. This work showed the effect of annealing time on intercalation of Li+ ion with WO3, however crystallinity can play a good role for electron movement, it cause a decrease in Li+ ion interaction with WO3.