This article investigates the dynamics of ion trapping and detrapping in electrochromic thin films, focusing on amorphous WO₃. Ion trapping is identified as a key factor in performance degradation, while detrapping is shown to restore the film's electrochromic properties. The study reveals that shallow traps form due to phase changes during cycling, leading to the formation of orthorhombic Li₂WO₄. Deep traps involve complex interactions between W⁴⁺, Li₂WO₄, and W⁴⁺-Li₂O, with the non-decomposable W⁴⁺-Li₂WO₄ couple being the source of irreversible traps. Additionally, bipolaron hopping between W⁴⁺ and W⁶⁺ sites contributes to optical absorption in the short-wavelength region. The research also demonstrates that ion trapping and detrapping occur in other cathodic electrochromic oxides, such as MoO₃, TiO₂, Nb₂O₅, and Ta₂O₅. The findings provide a comprehensive understanding of electrochromism based on polaron hopping and offer insights into the development of durable electrochromic devices. The study combines spectroelectrochemistry, XPS, and Raman spectroscopy to elucidate the trapping and detrapping mechanisms, highlighting the role of different W valences and the formation of Li₂WO₄ in the degradation process. The results emphasize the importance of understanding ion trapping dynamics for improving the performance and longevity of electrochromic materials.This article investigates the dynamics of ion trapping and detrapping in electrochromic thin films, focusing on amorphous WO₃. Ion trapping is identified as a key factor in performance degradation, while detrapping is shown to restore the film's electrochromic properties. The study reveals that shallow traps form due to phase changes during cycling, leading to the formation of orthorhombic Li₂WO₄. Deep traps involve complex interactions between W⁴⁺, Li₂WO₄, and W⁴⁺-Li₂O, with the non-decomposable W⁴⁺-Li₂WO₄ couple being the source of irreversible traps. Additionally, bipolaron hopping between W⁴⁺ and W⁶⁺ sites contributes to optical absorption in the short-wavelength region. The research also demonstrates that ion trapping and detrapping occur in other cathodic electrochromic oxides, such as MoO₃, TiO₂, Nb₂O₅, and Ta₂O₅. The findings provide a comprehensive understanding of electrochromism based on polaron hopping and offer insights into the development of durable electrochromic devices. The study combines spectroelectrochemistry, XPS, and Raman spectroscopy to elucidate the trapping and detrapping mechanisms, highlighting the role of different W valences and the formation of Li₂WO₄ in the degradation process. The results emphasize the importance of understanding ion trapping dynamics for improving the performance and longevity of electrochromic materials.