The study investigates the ion trapping and detrapping dynamics in amorphous tungsten oxide (α-WO₃), a model electrochromic material. Ion trapping is found to be responsible for performance degradation in electrochromic oxide thin films, and detrapping can rejuvenate the degraded films. The research reveals that shallow traps, composed of orthorhombic Li₂WO₄ formed during long-term cycling, degrade the colored state by suppressing small polaron hopping. Deep traps, composed of multiple-step processes involving mixed W⁴⁺-Li₂WO₄, amorphous Li₂WO₄, and W⁴⁺-Li₂O, degrade both the colored and bleached states. Irreversible traps, formed by non-decomposable W⁴⁺-Li₂WO₄, cause irreversible optical absorption in the short-wavelength region. The study also demonstrates that bipolaron hopping between W⁴⁺ and W⁶⁺ sites contributes to optical absorption in the short-wavelength region. The findings provide a comprehensive understanding of ion trapping and detrapping dynamics in α-WO₃, which is applicable to other cathodic electrochromic oxides, and offer insights for developing superior electrochromic devices with enhanced durability.The study investigates the ion trapping and detrapping dynamics in amorphous tungsten oxide (α-WO₃), a model electrochromic material. Ion trapping is found to be responsible for performance degradation in electrochromic oxide thin films, and detrapping can rejuvenate the degraded films. The research reveals that shallow traps, composed of orthorhombic Li₂WO₄ formed during long-term cycling, degrade the colored state by suppressing small polaron hopping. Deep traps, composed of multiple-step processes involving mixed W⁴⁺-Li₂WO₄, amorphous Li₂WO₄, and W⁴⁺-Li₂O, degrade both the colored and bleached states. Irreversible traps, formed by non-decomposable W⁴⁺-Li₂WO₄, cause irreversible optical absorption in the short-wavelength region. The study also demonstrates that bipolaron hopping between W⁴⁺ and W⁶⁺ sites contributes to optical absorption in the short-wavelength region. The findings provide a comprehensive understanding of ion trapping and detrapping dynamics in α-WO₃, which is applicable to other cathodic electrochromic oxides, and offer insights for developing superior electrochromic devices with enhanced durability.