Although　monovalent　lithium　has　been　successfully　used　as　a　coloring　ion　in　electrochromic　applications,　it　still　faces　the　challenges　of　low　safety,　high　cost,　and　limited　reserves.　Herein,　we　demonstrate　that　the　amorphous　WO3　films　intercalated　with　Al3+　ions　could　exhibit　desired　wide　optical　modulation　(similar　to　63.0%)　and　high　coloration　efficiency　(similar　to　72.0　cm(2)　A(-1),　which　is　＞100%　higher　than　that　with　Li+　or　Na+),　benefiting　from　the　three-electron　redox　properties　of　aluminum.　Due　to　the　strong　electrostatic　force　and　large　atomic　weight,　the　charge　exchange　processes　for　Al3+　ions　are　limited　only　to　the　near-surface　region　and　consequently　bring　about　enhanced　electrochromic　stability.　Our　findings　provide　in-depth　insights　into　the　nature　of　electrochromism　and　also　open　up　a　new　route　toward　scalable　electrochromic　devices　using　sputtering　techniques　and　earth-abundant　materials.