Devices　relying　on　reversible　ion　intercalation　are　used　in　sustainable　energy　technology,　for　example,　in　batteries,　in　rechargeable　electrical　and　electrochromic　(EC)　glazing　for　energy　efficient　buildings.　Degradation　of　electrochromic　thin　films　under　extended　charge　insertion/extraction　is　a　technologically　important　issue　for　which　no　in-depth　understanding　is　currently　available.　The　influence　of　coloration　depth　on　the　performance　characteristics　and　lifetime　of　electrochromic　WO3　materials　is　investigated　using　chronoamperometry　technology　in　this　work.　It　is　shown　that　depending　on　the　cycling　time,　and　the　applied　voltage,　two　different　types　of　adsorption　sites,　viz.　the　shallow　sites,　surrounded　by　low-energy　barriers　and　deep　sites　with　high-energy　barriers　are　created　in　the　WO3　host　structures.　During　the　bleaching　process,　higher　cycling　time　and　applied　voltage　create　a　large　coloration　depth　leading　to　trapped　immobile　Li+　ions　hindering　free　ion　transportation　and　subsequent　degradation　of　electrochromic　performance.　This　study　offers　a　new　understanding　on　the　degradation　mechanisms　of　the　electrochromic　materials　and　provides　a　general　guideline　suggesting　the　use　of　low　voltage　and　cycling　time　for　controlling　the　charge　insertion　and　extraction　in　electrochromic　materials　by　avoiding　the　large　coloring　depths.